OpenSSH through 7.7 is prone to a user enumeration vulnerability due to not delaying bailout for an invalid authenticating user until after the packet containing the request has been fully parsed, related to auth2-gss.c, auth2-hostbased.c, and auth2-pubkey.c.
CVE-2018-15473
“▲” beside the score: it is higher than NVD's CVSS score.
Score elevated to 9.0 because EPSS predicted 99% probability of exploitation within the next 30 days (99th percentile of EPSS-scored CVEs) when EchelonGraph scored this CVE. NVD baseline CVSS 5.3 retained for reference. Confidence: see factors.
- 5,913 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 99%
- Public exploit code is available (Metasploit, Exploit-DB, marked verified by Exploit-DB, other public proof-of-concept code)
A fix is available — apply it.
5,913 internet-facing services (distinct ip:port) on record running a version that maps to CVE-2018-15473, in our KEV-Exposure radar’s Shodan-derived sample.
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
- 5.3
- EG Score
- 9.0CRITICALhigh confidence
- EG Risk
- 63EG Risk 63/100
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)Severity53% × 45%Impact severity (EG Severity): CVSS 5.3 of 10. Never the KEV-floored or EPSS-lifted EG Score.Exploitation99% × 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
- 99%
- 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 5.3 MEDIUM): a likelihood of exploitation, not impact.
- EG Severity
- 5.3 MEDIUMCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
- EG Likelihood
- 99% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-22). 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: 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.
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
August 17, 2018
Last Modified
December 17, 2025
Advisory Details (9)
Auto-updated Oct 15, 2026[SECURITY] [DLA-1474-1] openssh security update
https://lists.debian.org/debian-lts-announce/2018/08/msg00022.htmlcommit 779974d35b48 (openbsd/src)
Fix landed in openbsd/src commit 779974d35b48 — awaiting tagged release
https://github.com/openbsd/src/commit/779974d35b4859c07bc3cb8a12c74b43b0a7d1e0#906236 - openssh: CVE-2018-15473: delay bailout for invalid authenticating user until after the packet - Debian Bug report logs
https://bugs.debian.org/906236Affected: Red Hat Enterprise Linux 7.
https://access.redhat.com/errata/RHSA-2019:2143Affected: Red Hat Enterprise Linux 6.
https://access.redhat.com/errata/RHSA-2019:0711oss-security - OpenSSH Username Enumeration
http://www.openwall.com/lists/oss-security/2018/08/15/5Patch Availability(3)
| Vendor / Ecosystem | Fix (by version range) / Patch | Released | Source |
|---|---|---|---|
| ubuntu | ssh-krb5 (1:7.2p2-4ubuntu2.6) @ xenial | 2026-10-23 | ubuntu |
| redhat | openssh-0:7.4p1-21.el7 | 2019-08-06 | redhat |
| redhat | openssh-0:5.3p1-124.el6_10 | 2019-04-09 | 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
(26 across 26 ecosystems)
Alpine:v3.10(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| openssh | — |
| — |
Alpine:v3.11(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| openssh | — |
| — |
Alpine:v3.12(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| openssh | — |
| — |
Alpine:v3.13(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| openssh | — |
| — |
Alpine:v3.14(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| openssh | — |
| — |
Alpine:v3.15(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| openssh | — |
| — |
Alpine:v3.16(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| openssh | — |
| — |
Alpine:v3.17(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| openssh | — |
| — |
Alpine:v3.18(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| openssh | — |
| — |
Alpine:v3.19(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| openssh | — |
| — |
Alpine:v3.20(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| openssh | — |
| — |
Alpine:v3.21(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| openssh | — |
| — |
Alpine:v3.22(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| openssh | — |
| — |
Alpine:v3.23(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| openssh | — |
| — |
Alpine:v3.24(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| openssh | — |
| — |
Alpine:v3.5(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| openssh | — |
| — |
Alpine:v3.6(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| openssh | — |
| — |
Alpine:v3.7(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| openssh | — |
| — |
Alpine:v3.8(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| openssh | — |
| — |
Alpine:v3.9(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: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, 1:6.7p1-5+deb8u3, 1:6.7p1-5+deb8u4 |
| — |
Debian:9(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| openssh | 1:7.4p1-10, 1:7.4p1-10+deb9u1, 1:7.4p1-10+deb9u2, 1:7.4p1-10+deb9u3 |
| — |
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
All Vendor Advisories
(3)
Every vendor that published an advisory referencing this CVE — pulled from our cve_vendor_advisories aggregation. Click any row for the vendor's original advisory page.
Data Freshness Timeline
(refreshed 25× in last 7d / 41× 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.
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. 7 repeat rows among the latest 86 are merged into the row they repeat.
- 2026-10-23 16:27 UTCEPSS rescoreEPSS 99% · 99th percentile
- 2026-10-23 16:19 UTCEG score recompute
- 2026-10-23 16:19 UTCVendor advisory
- 2026-10-23 16:19 UTCGHSA enrichmentGHSA-c8qw-h3f6-fv63 · GitHub CVSS 5.3
- 2026-10-22 16:27 UTCEPSS rescoreEPSS 99% · 99th percentile
- 2026-10-22 15:03 UTCEG score recompute
- 2026-10-22 15:03 UTCVendor advisory
- 2026-10-22 15:02 UTCGHSA enrichmentGHSA-c8qw-h3f6-fv63 · GitHub CVSS 5.3
- 2026-10-21 13:44 UTCEG score recompute
- 2026-10-21 13:44 UTCVendor advisory
- 2026-10-21 13:44 UTCGHSA enrichmentGHSA-c8qw-h3f6-fv63 · GitHub CVSS 5.3
- 2026-10-20 12:28 UTCEG score recompute
- 2026-10-20 12:28 UTCVendor advisory
- 2026-10-20 12:28 UTCGHSA enrichmentGHSA-c8qw-h3f6-fv63 · GitHub CVSS 5.3
- 2026-10-19 16:27 UTCEPSS rescoreEPSS 99% · 99th percentile
- 2026-10-19 11:11 UTCEG score recompute
- 2026-10-19 11:11 UTCVendor advisory
- 2026-10-19 11:11 UTCGHSA enrichmentGHSA-c8qw-h3f6-fv63 · GitHub CVSS 5.3
- 2026-10-18 16:27 UTCEPSS rescoreEPSS 99% · 99th percentile
- 2026-10-18 08:20 UTCEG score recompute
- 2026-10-18 08:20 UTCVendor advisory
- 2026-10-18 08:20 UTCGHSA enrichmentGHSA-c8qw-h3f6-fv63 · GitHub CVSS 5.3
- 2026-10-17 07:02 UTCEG score recompute
- 2026-10-17 07:02 UTCVendor advisory
- 2026-10-17 07:01 UTCGHSA enrichmentGHSA-c8qw-h3f6-fv63 · GitHub CVSS 5.3
Show 54 moreShow fewer
- 2026-10-16 05:44 UTCEG score recompute
- 2026-10-16 05:44 UTCVendor advisory
- 2026-10-16 05:44 UTCGHSA enrichmentGHSA-c8qw-h3f6-fv63 · GitHub CVSS 5.3
- 2026-10-15 16:27 UTCEPSS rescoreEPSS 99% · 99th percentile
- 2026-10-15 04:11 UTCEG score recompute
- 2026-10-15 04:11 UTCVendor advisory
- 2026-10-15 04:10 UTCGHSA enrichmentGHSA-c8qw-h3f6-fv63 · GitHub CVSS 5.3
- 2026-10-14 00:12 UTCEG score recompute
- 2026-10-14 00:12 UTCVendor advisory
- 2026-10-14 00:12 UTCGHSA enrichmentGHSA-c8qw-h3f6-fv63 · GitHub CVSS 5.3
- 2026-10-12 20:18 UTCVendor advisory
- 2026-10-12 20:18 UTCGHSA enrichmentGHSA-c8qw-h3f6-fv63 · GitHub CVSS 5.3
- 2026-10-12 20:17 UTCEG score recompute
- 2026-10-12 00:40 UTCEG score recompute
- 2026-09-30 09:54 UTCEG score recompute
- 2026-09-28 21:22 UTCOSV refresh
- 2026-09-21 20:27 UTCEPSS rescoreEPSS 99% · 99th percentile
- 2026-09-10 09:27 UTCEPSS rescoreEPSS 99% · 99th percentile
- 2026-09-09 01:44 UTCOSV refresh
- 2026-09-06 13:43 UTCEPSS rescoreEPSS 99% · 99th percentile
- 2026-09-05 15:24 UTCEPSS rescoreEPSS 99% · 99th percentile
- 2026-08-30 19:13 UTCEPSS rescoreEPSS 99% · 99th percentile
- 2026-08-28 21:36 UTCEPSS rescoreEPSS 99% · 99th percentile
- 2026-08-26 14:41 UTCEPSS rescoreEPSS 99% · 99th percentile
- 2026-08-22 11:07 UTCOSV refresh
- 2026-08-19 17:00 UTCEPSS rescoreEPSS 99% · 99th percentile
- 2026-08-18 13:43 UTCEPSS rescoreEPSS 99% · 99th percentile
- 2026-08-16 02:10 UTCEPSS rescoreEPSS 99% · 99th percentile
- 2026-08-11 13:36 UTCEPSS rescoreEPSS 99% · 99th percentile
- 2026-08-08 16:32 UTCEPSS rescoreEPSS 99% · 99th percentile
- 2026-08-06 13:45 UTCOSV refresh
- 2026-07-28 15:32 UTCEPSS rescoreEPSS 99% · 99th percentile
- 2026-07-24 14:14 UTCEPSS rescoreEPSS 99% · 99th percentile
- 2026-07-23 14:15 UTCEPSS rescoreEPSS 99% · 99th percentile
- 2026-07-23 01:33 UTCEG score recompute
- 2026-07-22 22:13 UTCEG score recompute
- 2026-07-21 06:48 UTCOSV refresh
- 2026-07-09 19:06 UTCEPSS rescoreEPSS 99% · 99th percentile
- 2026-07-05 02:27 UTCEPSS rescoreEPSS 99% · 99th percentile
- 2026-07-04 02:26 UTCOSV refresh
- 2026-06-15 17:45 UTCEPSS rescoreEPSS 99% · 99th percentile
- 2026-06-15 14:13 UTCOSV refresh
- 2026-06-13 22:58 UTCEPSS rescoreEPSS 90% · 99th percentile
- 2026-06-11 13:57 UTCEPSS rescoreEPSS 90% · 99th percentile
- 2026-06-10 13:19 UTCEPSS rescoreEPSS 90% · 99th percentile
- 2026-06-07 15:22 UTCEPSS rescoreEPSS 90% · 99th percentile
- 2026-06-05 22:44 UTCEPSS rescoreEPSS 90% · 99th percentile
- 2026-05-31 00:14 UTCEPSS rescoreEPSS 90% · 99th percentile
- 2026-05-29 13:41 UTCEPSS rescoreEPSS 90% · 99th percentile
- 2026-05-28 03:58 UTCEG score recompute
- 2026-05-28 03:58 UTCVendor advisory
- 2026-05-28 03:58 UTCGHSA enrichmentGHSA-c8qw-h3f6-fv63 · GitHub CVSS 5.3
- 2026-05-27 13:38 UTCEPSS rescoreEPSS 90% · 99th percentile
- 2026-05-26 13:42 UTCEPSS rescoreEPSS 90% · 99th percentile
Publicly available exploits
(14 references, 10 shown)Public exploit code is referenced for this CVE (1 Metasploit module, 3 Exploit-DB entries, 10 GitHub PoCs). Defenders should treat patch urgency accordingly.
- Exploit-DBEDB-45233✓ verifiedPublished Aug 21, 2018
OpenSSH 2.3 < 7.7 - Username Enumeration
Open source ↗ - Exploit-DBEDB-45210✓ verifiedPublished Aug 16, 2018
OpenSSH 2.3 < 7.7 - Username Enumeration (PoC)
Open source ↗ - Metasploitauxiliary/scanner/ssh/ssh_enumusers✓ verifiedPublished Apr 23, 2014
SSH Username Enumeration
Open source ↗ - GitHub PoCK3rn3l-32/Threaded-CVE-2018-15473Published Mar 25, 2026
A Python 3 reimplementation of the classic CVE-2018-15473 OpenSSH user enumeration exploit, extended with multi-threading, wordlist support, automatic vulnerability detection, and thread-safe exploit patching.
Open source ↗ - GitHub PoCsergiovks/SSH-User-Enum-Python3-CVE-2018-15473Published Mar 9, 2023
SSH User Enumerator in Python3, CVE-2018-15473, I updated the code of this exploit (https://www.exploit-db.com/exploits/45939) to work with python3 instead of python2.
Open source ↗ - GitHub PoCMrDottt/CVE-2018-15473Published Sep 14, 2021
CVE-2018-15473 Exploit
Open source ↗ - GitHub PoCSait-Nuri/CVE-2018-15473Published Nov 29, 2020
OpenSSH 2.3 < 7.7 - Username Enumeration
Open source ↗ - Exploit-DBEDB-45939Published Dec 4, 2018
OpenSSH < 7.7 - User Enumeration (2)
Open source ↗ - GitHub PoCJoeBlackSecurity/SSHUsernameBruter-SSHUBPublished Oct 31, 2018
Fully functional script for brute forcing SSH and trying credentials - CVE-2018-15473
Open source ↗ - GitHub PoCr3dxpl0it/CVE-2018-15473Published Oct 24, 2018
OpenSSH 7.7 - Username Enumeration
Open source ↗
Related CVEs(same product + same vendor + same CWE)
Same product
10 shownDebian:9:openssh · Alpine:v3.5:openssh · Alpine:v3.11:openssh
- CVE-2019-6111NVD 5.9EG 7.5EPSS p99HIGH
- CVE-2019-6109EG 6.8EPSS p90MEDIUM
- CVE-2018-20685EG 5.3EPSS p90MEDIUM
- CVE-2016-10012EG 7.8HIGH
- CVE-2016-10009NVD 7.3EG 7.5EPSS p99HIGH
- CVE-2016-10011EG 6.2MEDIUM
- CVE-2017-15906EG 5.3MEDIUM
- CVE-2016-10010EG 7.0EPSS p91HIGH
- CVE-2021-41617EG 7.0HIGH
- CVE-2021-28041EG 7.1HIGH
Frequently asked(5)
What is CVE-2018-15473?
When was CVE-2018-15473 made public?
Is CVE-2018-15473 actively exploited?
What is the CVSS score of CVE-2018-15473?
How do I remediate CVE-2018-15473?
Dependency Blast Radius
See which npm, PyPI, Go, and Maven packages are affected by CVE-2018-15473
Is Your Infrastructure Affected by CVE-2018-15473?
EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.