sshd in OpenSSH before 7.3, when SHA256 or SHA512 are used for user password hashing, uses BLOWFISH hashing on a static password when the username does not exist, which allows remote attackers to enumerate users by leveraging the timing difference between responses when a large password is provided.
CVE-2016-6210
CRITICALNVD 5.99.0Trending — 4 sources updated this weekWeaponizedEG-KEV Tier 2: WeaponizedEG-KEV is EchelonGraph's own tiering of exploitation signals from CISA KEV, CISA's SSVC data (Vulnrichment), ransomware data, public exploit-code references and EPSS.Tier 2 is not evidence of exploitation. It means a Metasploit module exists, or Exploit-DB marks a public exploit verified, or CISA's SSVC data says "public PoC" and EPSS is 50% or more. EchelonGraph does not test whether exploit code works.Signals for this CVE: a Metasploit module, CISA's SSVC exploitation value: public PoC, EPSS in the top 5%, EPSS 50% or more, other public exploit code (a GitHub or vendor proof of concept, or an Exploit-DB entry not marked verified).First public exploit code on record: 2014-04-23 (Metasploit auxiliary/scanner/ssh/ssh_enumusers)EchelonGraph confidence 74%: a heuristic from the tier and the number of signals, not a measured probability.
EchelonGraph scoreHIGH confidence
“▲” beside the score: it is higher than NVD's CVSS score.
Score elevated to 9.0 because EPSS predicted 89% probability of exploitation within the next 30 days (99th percentile of EPSS-scored CVEs) when EchelonGraph scored this CVE. NVD baseline CVSS 5.9 retained for reference. Confidence: see factors.
Triggered by: EPSS exploit prediction (continuous uplift above 30%)
Sources: EPSS, GitHub Security Advisory, NVD CVSS v3
Also known asEUVD-2016-7143 (ENISA EUVD) · GHSA-f525-65h3-3qjh (GitHub Security Advisories)Source: ENISA EUVD
9.0EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines (the SSVC decision on this page).
- 494 internet-facing services (distinct ip:port) on record running an affected version — derived from Shodan data (© Shodan); a patched service can stay counted while its port stays open
- High exploitation likelihood — EPSS 89%
- Public exploit code is available (Metasploit, other public proof-of-concept code)
CISA-KEV: Not listedEPSS PROB: 89%CVSS: 5.9Exploit: Metasploit · other public PoCExposed services: 494
A fix is available — apply it.
Internet exposure · derived from Shodan data
494 internet-facing services (distinct ip:port) on record running a version that maps to CVE-2016-6210, in our KEV-Exposure radar’s Shodan-derived sample.
across 30 countries (China, United States, Germany, Japan, Singapore)top: openssh
See the KEV-Exposure radar →Derived from Shodan data. Shodan data is owned by Shodan, which holds its copyright (© Shodan). EchelonGraph claims no ownership of it or copyright in it. Aggregate, host-redacted.
How it counts: every 12 hours, when Shodan query credits allow, the radar runs one Shodan query per tracked product, reads up to 100 ip:port services per query, and keeps a service when its banner version matches a CISA-KEV or high-EPSS CVE; a service is dropped when neither a search nor a Shodan InternetDB port re-check has refreshed it for 21 days. A re-check that finds the port still listed by Shodan InternetDB refreshes the service without re-reading the banner, so a patched service can stay counted while its port stays open. A count is a banner-version inference over a sample, not an exploit test and not an internet-wide census, and the unit is a service, not a machine: a machine answering on two ports counts twice.
- CVSS v3
- 5.9
- EG Score
- 9.0CRITICALhigh confidence
- EG Risk
- 62EG Risk 62/100
EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.
How it’s computed (value × EchelonGraph’s weight)Severity59% × 45%Impact severity (EG Severity): CVSS 5.9 of 10. Never the KEV-floored or EPSS-lifted EG Score.Exploitation89% × 40%FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.Automatability0% × 15%CISA's SSVC Automatable value: no (Vulnrichment).SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Track* at high (mission-essential systems).Exploitation public PoC (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.Action: A fix is available. Apply it within your standard update timelines. - EPSS PROB
- 89%
- EPSS %ILE
- 99th
- KEV
- Not listed
What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)
The EG score (9.0): severity, escalated by confirmed exploitation. This CVE's 9.0 is EPSS's lift toward 9.0 from its impact severity (EG Severity, CVSS 5.9 MEDIUM): a likelihood of exploitation, not impact.
- EG Severity
- 5.9 MEDIUMCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
- EG Likelihood
- 89% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-11-09). FIRST's exploitation probability, not an EchelonGraph model.
- Confirmed exploitation
- None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
- EG Priority
- SSVC Track at medium mission impactTrack at low or medium mission impact; Track* at high (mission-essential systems).CISA BOD 26-04: 60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.
SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Track* at high (mission-essential systems).
A fix is available. Apply it within your standard update timelines.
Exploitation public PoC (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table
BOD 26-04 (CISA's remediation timeline, Table 1)60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.
The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it
Published
February 13, 2017
Last Modified
June 17, 2026
Advisory Details (9)
Auto-updated Oct 14, 2026Patch available. Sources: redhat.
Web page
OpenSSHd 7.2p2 - Username Enumeration - Linux remote Exploit
https://www.exploit-db.com/exploits/40113/Web page
OpenSSH: Multiple vulnerabilities (GLSA 201612-18) — Gentoo security
https://security.gentoo.org/glsa/201612-18Red HatMentions a patch (unverified)
Affected: Red Hat Enterprise Linux 6.
https://access.redhat.com/errata/RHSA-2017:2563Red HatMentions a patch (unverified)
Affected: Red Hat Enterprise Linux 7.
https://access.redhat.com/errata/RHSA-2017:2029Vendor Advisories for CVE-2016-6210(2)
These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.
- CVE-2016-6210Microsoft Security Response Center (MSRC)Medium
sshd in OpenSSH before 7.3, when SHA256 or SHA512 are used for user password hashing, uses BLOWFISH hashing on a static password when the username does not exist, which allows remote attackers to enumerate users by leveraging the timing difference between responses when a large password is provided.
- CVE-2016-6210Palo Alto Networks Security AdvisoriesMedium
CVE-2016-6210 OpenSSH Vulnerability
Patch Availability(3)
| Vendor / Ecosystem | Fix (by version range) / Patch | Released | Source |
|---|---|---|---|
| ubuntu | ssh-krb5 (1:7.2p2-4ubuntu2.1) @ xenial | 2026-11-03 | ubuntu |
| redhat | openssh-0:5.3p1-123.el6_9 | 2017-08-31 | redhat |
| redhat | openssh-0:7.4p1-11.el7 | 2017-08-01 | redhat |
Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.
Affected Packages
(9 across 9 ecosystems)
Alpine:v3.2(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| openssh | — |
| — |
Alpine:v3.3(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| openssh | — |
| — |
Alpine:v3.4(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| openssh | — |
| — |
Debian:11(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| openssh | — |
| — |
Debian:12(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| openssh | — |
| — |
Debian:13(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| openssh | — |
| — |
Debian:14(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| openssh | — |
| — |
Debian:7(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| openssh | 1:6.0p1-4, 1:6.0p1-4+deb7u1, 1:6.0p1-4+deb7u2, 1:6.0p1-4+deb7u3, 1:6.0p1-4+deb7u4 |
| — |
Debian:8(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| openssh | 1:6.7p1-5, 1:6.7p1-5+deb8u1, 1:6.7p1-5+deb8u2 |
| — |
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Additional Vendor Advisories
(3)
Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.
Data Freshness Timeline
(refreshed 25× in last 7d / 99× in last 30d)
Each row is a time one of our pipelines fetched, updated or re-scored this CVE. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.
Showing the most recent 100 of 169 refreshes on record for this CVE.
A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. None are among the latest 100 rows. The 69 oldest rows on record are not shown and were not checked, so the counts can still include repeats.
- 2026-11-10 07:09 UTCEG score recompute
- 2026-11-10 07:09 UTCVendor advisory
- 2026-11-10 07:09 UTCGHSA enrichmentGHSA-f525-65h3-3qjh · GitHub severity MODERATE · GitHub CVSS 5.9
- 2026-11-09 07:11 UTCEG score recompute
- 2026-11-09 07:11 UTCVendor advisory
- 2026-11-09 07:11 UTCGHSA enrichmentGHSA-f525-65h3-3qjh · GitHub severity MODERATE · GitHub CVSS 5.9
- 2026-11-08 16:29 UTCEPSS rescoreEPSS 89% · 99th percentile
- 2026-11-08 07:14 UTCEG score recompute
- 2026-11-08 07:14 UTCVendor advisory
- 2026-11-08 07:14 UTCGHSA enrichmentGHSA-f525-65h3-3qjh · GitHub severity MODERATE · GitHub CVSS 5.9
- 2026-11-07 16:29 UTCEPSS rescoreEPSS 89% · 99th percentile
- 2026-11-07 07:14 UTCEG score recompute
- 2026-11-07 07:14 UTCVendor advisory
- 2026-11-07 07:14 UTCGHSA enrichmentGHSA-f525-65h3-3qjh · GitHub severity MODERATE · GitHub CVSS 5.9
- 2026-11-06 07:17 UTCEG score recompute
- 2026-11-06 07:17 UTCVendor advisory
- 2026-11-06 07:17 UTCGHSA enrichmentGHSA-f525-65h3-3qjh · GitHub severity MODERATE · GitHub CVSS 5.9
- 2026-11-05 16:27 UTCEPSS rescoreEPSS 89% · 99th percentile
- 2026-11-05 07:21 UTCEG score recompute
- 2026-11-05 07:21 UTCVendor advisory
- 2026-11-05 07:21 UTCGHSA enrichmentGHSA-f525-65h3-3qjh · GitHub severity MODERATE · GitHub CVSS 5.9
- 2026-11-04 16:27 UTCEPSS rescoreEPSS 89% · 99th percentile
- 2026-11-04 07:25 UTCEG score recompute
- 2026-11-04 07:25 UTCVendor advisory
- 2026-11-04 07:25 UTCGHSA enrichmentGHSA-f525-65h3-3qjh · GitHub severity MODERATE · GitHub CVSS 5.9
Show 75 moreShow fewer
- 2026-11-03 07:29 UTCEG score recompute
- 2026-11-03 07:29 UTCVendor advisory
- 2026-11-03 07:29 UTCGHSA enrichmentGHSA-f525-65h3-3qjh · GitHub severity MODERATE · GitHub CVSS 5.9
- 2026-11-02 11:55 UTCOSV refresh
- 2026-11-02 07:33 UTCEG score recompute
- 2026-11-02 07:33 UTCVendor advisory
- 2026-11-02 07:33 UTCGHSA enrichmentGHSA-f525-65h3-3qjh · GitHub severity MODERATE · GitHub CVSS 5.9
- 2026-11-01 07:38 UTCEG score recompute
- 2026-11-01 07:38 UTCVendor advisory
- 2026-11-01 07:38 UTCGHSA enrichmentGHSA-f525-65h3-3qjh · GitHub severity MODERATE · GitHub CVSS 5.9
- 2026-10-31 16:27 UTCEPSS rescoreEPSS 89% · 99th percentile
- 2026-10-31 07:41 UTCEG score recompute
- 2026-10-31 07:41 UTCVendor advisory
- 2026-10-31 07:41 UTCGHSA enrichmentGHSA-f525-65h3-3qjh · GitHub CVSS 5.9
- 2026-10-30 07:46 UTCEG score recompute
- 2026-10-30 07:46 UTCVendor advisory
- 2026-10-30 07:46 UTCGHSA enrichmentGHSA-f525-65h3-3qjh · GitHub CVSS 5.9
- 2026-10-29 07:50 UTCEG score recompute
- 2026-10-29 07:50 UTCVendor advisory
- 2026-10-29 07:50 UTCGHSA enrichmentGHSA-f525-65h3-3qjh · GitHub CVSS 5.9
- 2026-10-28 16:26 UTCEPSS rescoreEPSS 89% · 99th percentile
- 2026-10-28 07:55 UTCEG score recompute
- 2026-10-28 07:55 UTCVendor advisory
- 2026-10-28 07:55 UTCGHSA enrichmentGHSA-f525-65h3-3qjh · GitHub CVSS 5.9
- 2026-10-27 08:00 UTCEG score recompute
- 2026-10-27 08:00 UTCVendor advisory
- 2026-10-27 08:00 UTCGHSA enrichmentGHSA-f525-65h3-3qjh · GitHub CVSS 5.9
- 2026-10-26 05:41 UTCVendor advisory
- 2026-10-26 05:40 UTCGHSA enrichmentGHSA-f525-65h3-3qjh · GitHub CVSS 5.9
- 2026-10-25 19:45 UTCEG score recompute
- 2026-10-25 16:27 UTCEPSS rescoreEPSS 89% · 99th percentile
- 2026-10-25 05:43 UTCEG score recompute
- 2026-10-25 05:43 UTCVendor advisory
- 2026-10-25 05:42 UTCGHSA enrichmentGHSA-f525-65h3-3qjh · GitHub CVSS 5.9
- 2026-10-24 05:47 UTCEG score recompute
- 2026-10-24 05:47 UTCVendor advisory
- 2026-10-24 05:46 UTCGHSA enrichmentGHSA-f525-65h3-3qjh · GitHub CVSS 5.9
- 2026-10-23 05:47 UTCEG score recompute
- 2026-10-23 05:47 UTCVendor advisory
- 2026-10-23 05:47 UTCGHSA enrichmentGHSA-f525-65h3-3qjh · GitHub CVSS 5.9
- 2026-10-22 05:51 UTCEG score recompute
- 2026-10-22 05:51 UTCVendor advisory
- 2026-10-22 05:51 UTCGHSA enrichmentGHSA-f525-65h3-3qjh · GitHub CVSS 5.9
- 2026-10-21 16:27 UTCEPSS rescoreEPSS 89% · 99th percentile
- 2026-10-21 05:56 UTCEG score recompute
- 2026-10-21 05:56 UTCVendor advisory
- 2026-10-21 05:55 UTCGHSA enrichmentGHSA-f525-65h3-3qjh · GitHub CVSS 5.9
- 2026-10-20 05:59 UTCEG score recompute
- 2026-10-20 05:59 UTCVendor advisory
- 2026-10-20 05:58 UTCGHSA enrichmentGHSA-f525-65h3-3qjh · GitHub CVSS 5.9
- 2026-10-19 06:02 UTCEG score recompute
- 2026-10-19 06:02 UTCVendor advisory
- 2026-10-19 06:02 UTCGHSA enrichmentGHSA-f525-65h3-3qjh · GitHub CVSS 5.9
- 2026-10-18 06:05 UTCEG score recompute
- 2026-10-18 06:05 UTCVendor advisory
- 2026-10-18 06:05 UTCGHSA enrichmentGHSA-f525-65h3-3qjh · GitHub CVSS 5.9
- 2026-10-17 06:06 UTCEG score recompute
- 2026-10-17 06:06 UTCVendor advisory
- 2026-10-17 06:05 UTCGHSA enrichmentGHSA-f525-65h3-3qjh · GitHub CVSS 5.9
- 2026-10-16 06:09 UTCEG score recompute
- 2026-10-16 06:09 UTCVendor advisory
- 2026-10-16 06:08 UTCGHSA enrichmentGHSA-f525-65h3-3qjh · GitHub CVSS 5.9
- 2026-10-15 16:26 UTCEPSS rescoreEPSS 89% · 99th percentile
- 2026-10-15 04:45 UTCEG score recompute
- 2026-10-15 04:45 UTCVendor advisory
- 2026-10-15 04:45 UTCGHSA enrichmentGHSA-f525-65h3-3qjh · GitHub CVSS 5.9
- 2026-10-14 16:27 UTCEPSS rescoreEPSS 89% · 99th percentile
- 2026-10-14 00:38 UTCEG score recompute
- 2026-10-14 00:38 UTCVendor advisory
- 2026-10-14 00:37 UTCGHSA enrichmentGHSA-f525-65h3-3qjh · GitHub CVSS 5.9
- 2026-10-12 20:42 UTCVendor advisory
- 2026-10-12 20:42 UTCGHSA enrichmentGHSA-f525-65h3-3qjh · GitHub CVSS 5.9
- 2026-10-12 20:41 UTCEG score recompute
- 2026-10-12 01:05 UTCEG score recompute
- 2026-10-09 20:01 UTCEPSS rescoreEPSS 89% · 99th percentile
Publicly available exploits
(5 references)Public exploit code is referenced for this CVE (1 Metasploit module, 2 Exploit-DB entries, 2 GitHub PoCs). Defenders should treat patch urgency accordingly.
- Metasploitauxiliary/scanner/ssh/ssh_enumusers✓ verifiedPublished Apr 23, 2014
SSH Username Enumeration
Open source ↗ - GitHub PoCserexp/poc-CVE20166210Published May 2, 2026
CVE-2016-6210/Openssh 7.2p2 side channel info disclosure POC
Open source ↗ - GitHub PoCjustlce/CVE-2016-6210-ExploitPublished Aug 25, 2019
OpenSSH Username Enumeration - CVE-2016-6210
Open source ↗ - Exploit-DBEDB-40136Published Jul 20, 2016
OpenSSH 7.2p2 - Username Enumeration
Open source ↗ - Exploit-DBEDB-40113Published Jul 18, 2016
OpenSSHd 7.2p2 - Username Enumeration
Open source ↗
Related CVEs(same product + same vendor + same CWE)
Same product
10 shownAlpine:v3.2:openssh · Alpine:v3.3:openssh · Alpine:v3.4:openssh
- CVE-2016-6515NVD 7.5EG 8.3EPSS p99HIGH
- CVE-2016-10011EG 6.2MEDIUM
- CVE-2016-10010EG 7.0EPSS p91HIGH
- CVE-2016-10012EG 7.8HIGH
- CVE-2016-10009NVD 7.3EG 7.5EPSS p99HIGH
- CVE-2015-8325EG 7.8HIGH
- CVE-2017-15906EG 5.3MEDIUM
- CVE-2016-0778EG 8.1EPSS p98HIGH
- CVE-2016-0777NVD 6.5EG 8.0EPSS p99HIGH
- CVE-2016-10708EG 7.5EPSS p97HIGH
Same vendor
5 shownredhat:RHSA-2017:2029
Frequently asked(5)
What is CVE-2016-6210?
CVE-2016-6210 is a critical-severity vulnerability; its CVE record was published on February 13, 2017. sshd in OpenSSH before 7.3, when SHA256 or SHA512 are used for user password hashing, uses BLOWFISH hashing on a static password when the username does not exist, which allows remote attackers to enumerate users by leveraging the timing difference between responses when a large password is provided.
When was CVE-2016-6210 made public?
CVE-2016-6210 was made public on July 14, 2016: that is the date its CVE record's CNA, MITRE Corporation, gives for when the vulnerability was made public. The CVE record itself was published on February 13, 2017. EchelonGraph's copy of the record carries a last-modified date of June 17, 2026; the record at its source may have been updated since.
Is CVE-2016-6210 actively exploited?
CVE-2016-6210 is not currently on CISA's Known Exploited Vulnerabilities catalog. EchelonGraph's EG-KEV model places it in Tier 2 (Weaponized), which is not evidence of exploitation: a Metasploit module exists for it, and CISA's SSVC data says a public PoC exists and its EPSS is 50% or more. EchelonGraph does not test whether exploit code works. FIRST EPSS estimates a 89% probability of exploitation in the next 30 days (99th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2016-6210?
CVE-2016-6210 has a CVSS v3 base score of 5.9 (NVD). EchelonGraph synthesises NVD + FIRST EPSS + GHSA into a combined EG score of 9.0 (CRITICAL).
How do I remediate CVE-2016-6210?
A fix for CVE-2016-6210 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2016-6210 are linked in the Vendor Advisories panel on this page.
Dependency Blast Radius
See which npm, PyPI, Go, and Maven packages are affected by CVE-2016-6210
Is Your Infrastructure Affected by CVE-2016-6210?
EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.