Serialized-object interfaces in certain Cisco Collaboration and Social Media; Endpoint Clients and Client Software; Network Application, Service, and Acceleration; Network and Content Security Devices; Network Management and Provisioning; Routing and Switching - Enterprise and Service Provider; Unified Computing; Voice and Unified Communications Devices; Video, Streaming, TelePresence, and Transcoding Devices; Wireless; and Cisco Hosted Services products allow remote attackers to execute arbitrary commands via a crafted serialized Java object, related to the Apache Commons Collections (ACC) library.
CVE-2015-6420
CRITICALNVD 9.89.8Trending — 3 sources updated this weekElevatedEG-KEV Tier 3: ElevatedEG-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 3 is not evidence of exploitation. It means public exploit code is referenced, or CISA's SSVC data says "public PoC", or EPSS ranks the CVE in the top 5%.Signals for this CVE: EPSS in the top 5%.EchelonGraph confidence 38%: a heuristic from the tier and the number of signals, not a measured probability.
EchelonGraph scoreLOW confidence
This critical-severity CVE scores 9.8 under NVD CVSS v3. EPSS exploit-prediction score not yet available (the EPSS model rescores nightly; freshly-published CVEs typically appear within 48 hours). GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).
Triggered by: NVD CVSS baseline
Sources: nvd
9.8EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines at low or medium mission impact and sooner than that at high (the SSVC decision on this page).
- High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 19%CVSS: 9.8Exploit: No code on recordExposed services: Not assessed
A fix is available — apply it.
- CVSS v3
- 9.8
- EG Score
- 9.8CRITICALlow confidence
- EG Risk
- 59EG Risk 59/100
EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).
How it’s computed (value × EchelonGraph’s weight)Severity98% × 45%The EG Score, 9.8 of 10.Exploitation0% × 40%No KEV listing, EG-KEV tier or EPSS when EchelonGraph scored this CVE.Automatability100% × 15%CISA's SSVC Automatable value: yes (Vulnrichment).SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Attend at high (mission-essential systems).Exploitation none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact total (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 at low or medium mission impact and sooner than that at high. - EPSS PROB
- 19%
- EPSS %ILE
- 97th
- KEV
- Not listed
SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Attend at high (mission-essential systems).
A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
Exploitation none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact total (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
Published
December 15, 2015
Last Modified
October 7, 2026
Advisory Details (8)
Auto-updated Oct 7, 2026Patch available. Sources: cert.
generic
Pony Mail
https://lists.apache.org/thread.html/r352e40ca9874d1beb4ad95403792adca7eb295e6bc3bd7b65fabcc21%40%3Ccommits.samza.apache.org%3Egeneric
[R1] Cisco Unified Customer Voice Portal Java Deserialization Remote Code Execution - Research Advisory | Tenable®
https://www.tenable.com/security/research/tra-2017-14cert
VU#581311 - TP-Link EAP Controller lacks RMI authentication and is vulnerable to deserialization attacks
https://www.kb.cert.org/vuls/id/581311generic
[R1] Cisco Security Manager and Prime LMS Java Deserialization Remote Code Execution - Research Advisory | Tenable®
https://www.tenable.com/security/research/tra-2017-23generic
Vulnerability in Java Deserialization Affecting Cisco Products
http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20151209-java-deserializationAffected Packages
(5 across 1 ecosystem)
Maven(5)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| commons-collections:commons-collections | 1.0 ... 3.2.1 (12 versions) |
| — |
| net.sourceforge.collections:collections-generic | — |
| — |
| org.apache.commons:commons-collections4 | 4.0 |
| — |
| org.apache.servicemix.bundles:org.apache.servicemix.bundles.collections-generic | — |
| — |
| org.apache.servicemix.bundles:org.apache.servicemix.bundles.commons-collections | — |
| — |
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 8× in last 7d / 8× 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.
- 2026-10-11 13:40 UTCEPSS rescoreEPSS 19% · 97th percentile
- 2026-10-10 19:54 UTCEPSS rescoreEPSS 19% · 97th percentile
- 2026-10-09 20:01 UTCEPSS rescoreEPSS 19% · 97th percentile
- 2026-10-08 16:35 UTCEPSS rescoreEPSS 19% · 97th percentile
- 2026-10-07 23:40 UTCEPSS rescoreEPSS 19% · 97th percentile
- 2026-10-07 18:40 UTCEG score recompute
- 2026-10-07 18:02 UTCEG score recompute
- 2026-10-07 18:01 UTCMITRE cvelistV5first tracked
Related CVEs(same CWE)
Same CWE
10 shownCWE-502
- CVE-2015-7450EG 9.8 KEVEPSS p100CRITICAL
- CVE-2015-4852EG 9.8 KEVEPSS p100CRITICAL
- CVE-2016-1114EG 9.8EPSS p95CRITICAL
- CVE-2016-7124EG 9.8EPSS p97CRITICAL
- CVE-2016-4978EG 7.2EPSS p94HIGH
- CVE-2016-6330EG 9.8EPSS p96CRITICAL
- CVE-2016-4385EG 7.3EPSS p91HIGH
- CVE-2016-5019EG 9.8EPSS p95CRITICAL
- CVE-2016-7065EG 8.8EPSS p96HIGH
- CVE-2016-6620EG 9.8CRITICAL
Frequently asked(5)
What is CVE-2015-6420?
CVE-2015-6420 is a critical-severity vulnerability; its CVE record was published on December 15, 2015. Serialized-object interfaces in certain Cisco Collaboration and Social Media; Endpoint Clients and Client Software; Network Application, Service, and Acceleration; Network and Content Security Devices; Network Management and Provisioning; Routing and Switching - Enterprise and Service Provider;…
When was CVE-2015-6420 made public?
CVE-2015-6420 was made public on December 9, 2015: that is the date its CVE record's CNA, Cisco Systems, Inc., gives for when the vulnerability was made public. The CVE record itself was published on December 15, 2015. EchelonGraph's copy of the record carries a last-modified date of October 7, 2026; the record at its source may have been updated since.
Is CVE-2015-6420 actively exploited?
CVE-2015-6420 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 19% probability of exploitation in the next 30 days (97th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2015-6420?
CVE-2015-6420 has a CVSS v3 base score of 9.8 (NVD). The EG score is currently aggregating — additional source signals are being incorporated as they become available..
How do I remediate CVE-2015-6420?
A fix for CVE-2015-6420 is available: update to the fixed version the vendor names in its advisory.
Dependency Blast Radius
See which npm, PyPI, Go, and Maven packages are affected by CVE-2015-6420
Is Your Infrastructure Affected by CVE-2015-6420?
EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.