CVE-2015-6563

MEDIUMNVD 6.46.4
EchelonGraph scoreMEDIUM confidence

“—” beside the score: it is equal to NVD's CVSS score.

Score 6.4 from GitHub Security Advisory (severity: LOW) published 2022-05-14. NVD baseline CVSS 6.4; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: EPSS, GitHub Security Advisory, NVD CVSS v3

Also known asEUVD-2015-6502 (ENISA EUVD) · GHSA-2f6c-wrfr-f7rw (GitHub Security Advisories)Source: ENISA EUVD

6.4EG
EchelonGraph verdictMonitorRemediate within your standard update timelines (the SSVC decision on this page).
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0.4%CVSS: 6.4Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

The monitor component in sshd in OpenSSH before 7.0 on non-OpenBSD platforms accepts extraneous username data in MONITOR_REQ_PAM_INIT_CTX requests, which allows local users to conduct impersonation attacks by leveraging any SSH login access in conjunction with control of the sshd uid to send a crafted MONITOR_REQ_PWNAM request, related to monitor.c and monitor_wrap.c.

CVSS v3
6.4
EG Score
6.4MEDIUMmedium confidence
EG Risk
29
EG Risk 29/100

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)
Severity64% × 45%
Impact severity (EG Severity): CVSS 6.4 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation0.4% × 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 none (CISA Vulnrichment) · Automatable no (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.
EPSS PROB
0.4%
EPSS %ILE
32nd
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 (6.4): severity, escalated by confirmed exploitation. This CVE's 6.4 is its impact severity (EG Severity), not escalated.

EG Severity
6.4 MEDIUMCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
EG Likelihood
0.4% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-26). 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: 14 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 none (CISA Vulnrichment) · Automatable no (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

BOD 26-04 (CISA's remediation timeline, Table 1)14 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 total (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 24, 2015

Last Modified

May 27, 2026

Advisory Details (4)

Auto-updated Jul 17, 2026
Patch available.
Web page

oss-security - Re: CVE request - OpenSSH 6.9 PAM privilege separation vulnerabilities

http://www.openwall.com/lists/oss-security/2015/08/22/1
Web page
http://www.openssh.com/txt/release-7.0
Web page

Full Disclosure: BFS-SA-2015-002: OpenSSH PAM Privilege Separation Vulnerabilities

http://seclists.org/fulldisclosure/2015/Aug/54
Web page
http://rhn.redhat.com/errata/RHSA-2016-0741.html

Vendor Advisories for CVE-2015-6563(3)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(2)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
redhatopenssh-0:5.3p1-117.el62016-05-10redhat
redhatopenssh-0:6.6.1p1-22.el72015-11-19redhat

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

(5 across 5 ecosystems)
Debian:11(1)
PackageVulnerable rangeFix by version rangeDependents
openssh—
  • every version up to 1:6.9p1-1: fixed in 1:6.9p1-1
—
Debian:12(1)
PackageVulnerable rangeFix by version rangeDependents
openssh—
  • every version up to 1:6.9p1-1: fixed in 1:6.9p1-1
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
openssh—
  • every version up to 1:6.9p1-1: fixed in 1:6.9p1-1
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
openssh—
  • every version up to 1:6.9p1-1: fixed in 1:6.9p1-1
—
Debian:8(1)
PackageVulnerable rangeFix by version rangeDependents
openssh1:6.7p1-5 ... 1:6.7p1-5+deb8u5 (6 versions)
  • every version up to 1:6.7p1-5+deb8u6: fixed in 1:6.7p1-5+deb8u6
—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 7× in last 7d / 33× 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 its CVE.org record (CNA or CISA ADP). 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). "EchelonGraph re-scored" is our own recompute of this CVE's score, not an update from a source, and is not counted in the refreshes above. Most recent first.

Showing the most recent 100 of 208 rows on record for this CVE, as 97 entries (3 repeats merged).

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. 3 repeat rows among the latest 100 are merged into the row they repeat. The 108 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-11-12 16:27 UTCEPSS rescoreEPSS 0.4% · 32nd percentile
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  18. 2026-10-27 10:42 UTCEchelonGraph re-scored
  19. 2026-10-27 10:42 UTCVendor advisory
  20. 2026-10-27 10:42 UTCGHSA enrichmentGHSA-2f6c-wrfr-f7rw · GitHub severity LOW · GitHub CVSS 6.4
  21. 2026-10-26 16:26 UTCEPSS rescoreEPSS 0.4% · 31st percentile
  22. 2026-10-25 19:53 UTCEchelonGraph re-scored
  23. 2026-10-25 16:26 UTCEPSS rescoreEPSS 0.4% · 31st percentile
  24. 2026-10-24 16:27 UTCEPSS rescoreEPSS 0.4% · 30th percentile
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  1. 2026-10-22 16:27 UTCEPSS rescoreEPSS 0.4% · 30th percentile
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  6. 2026-10-18 11:00 UTCEchelonGraph re-scored
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  9. 2026-10-16 13:24 UTCOSV refresh
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  13. 2026-10-12 20:50 UTCEchelonGraph re-scored
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  15. 2026-10-12 01:13 UTCEchelonGraph re-scored
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  26. 2026-09-30 09:06 UTCEchelonGraph re-scored
  27. 2026-09-28 13:45 UTCEPSS rescoreEPSS 0.4% · 29th percentile
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  30. 2026-09-24 19:46 UTCOSV refresh
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  43. 2026-09-05 12:00 UTCOSV refresh
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  55. 2026-08-18 13:43 UTCEPSS rescoreEPSS 0.4% · 31st percentile
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Frequently asked(5)

What is CVE-2015-6563?
CVE-2015-6563 is a medium-severity vulnerability; its CVE record was published on August 24, 2015. The monitor component in sshd in OpenSSH before 7.0 on non-OpenBSD platforms accepts extraneous username data in MONITOR_REQ_PAM_INIT_CTX requests, which allows local users to conduct impersonation attacks by leveraging any SSH login access in conjunction with control of the sshd uid to send a…
When was CVE-2015-6563 made public?
CVE-2015-6563 was made public on August 1, 2015: 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 August 24, 2015. EchelonGraph's copy of the record carries a last-modified date of May 27, 2026; the record at its source may have been updated since.
Is CVE-2015-6563 actively exploited?
CVE-2015-6563 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.4% probability of exploitation in the next 30 days (32nd percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2015-6563?
CVE-2015-6563 has a CVSS v3 base score of 6.4 (NVD).
How do I remediate CVE-2015-6563?
A fix for CVE-2015-6563 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2015-6563 are linked in the Vendor Advisories panel on this page.

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