CVE-2017-6542

CRITICALNVD 9.89.8—
EchelonGraph scoreMEDIUM confidence

Score 9.8 from GitHub Security Advisory (severity: CRITICAL) published 2022-05-14. NVD baseline CVSS 9.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
Weaponized
9.8EG
EchelonGraph verdictPatch this weekExploitation is likely or a public exploit exists.
  • Public exploit code is available (Exploit-DB (verified), epss top5pct, public exploit)
CISA-KEV: Not listedEPSS PROB: 22%CVSS: 9.8Exploit: Exploit-DB (verified) · epss top5pct · public exploitExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

The ssh_agent_channel_data function in PuTTY before 0.68 allows remote attackers to have unspecified impact via a large length value in an agent protocol message and leveraging the ability to connect to the Unix-domain socket representing the forwarded agent connection, which trigger a buffer overflow.

CVSS v3
9.8
EG Score
9.8(medium)
EG Risk
75(Track*)
EG Risk 75/100SSVC: Track*

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
Severity98% × 45%
Exploitation65% × 40%
Automatability30% × 15%
Action: Watch closely — could escalate to Attend.
EPSS PROB
22%
EPSS %ILE
97%
KEV
Not listed

Published

March 27, 2017

Last Modified

June 17, 2026

Advisory Details (6)

Auto-updated Aug 17, 2026
🔬 Proof of concept available. No patch confirmed yet.
generic🟡 PoC Available

PuTTY < 0.68 - 'ssh_agent_channel_data' Integer Overflow Heap Corruption - Linux dos Exploit

https://www.exploit-db.com/exploits/42137/
generic

FileZilla: Buffer overflow (GLSA 201706-09) — Gentoo security

https://security.gentoo.org/glsa/201706-09
generic

PuTTY: Buffer overflow (GLSA 201703-03) — Gentoo security

https://security.gentoo.org/glsa/201703-03
generic
http://www.securitytracker.com/id/1038067
generic

SecurityFocus

http://www.securityfocus.com/bid/97156
generic🟡 PoC Available

PuTTY vulnerability vuln-agent-fwd-overflow

http://www.chiark.greenend.org.uk/~sgtatham/putty/wishlist/vuln-agent-fwd-overflow.html

Affected Packages

(8 across 8 ecosystems)
Alpine:v3.2(1)
PackageVulnerable rangeFixed inDependents
putty—0.68-r0—
Alpine:v3.3(1)
PackageVulnerable rangeFixed inDependents
putty—0.68-r0—
Alpine:v3.4(1)
PackageVulnerable rangeFixed inDependents
putty—0.68-r0—
Alpine:v3.5(1)
PackageVulnerable rangeFixed inDependents
putty—0.68-r0—
Debian:11(1)
PackageVulnerable rangeFixed inDependents
putty—0.67-3—
Debian:12(1)
PackageVulnerable rangeFixed inDependents
putty—0.67-3—
Debian:13(1)
PackageVulnerable rangeFixed inDependents
putty—0.67-3—
Debian:14(1)
PackageVulnerable rangeFixed inDependents
putty—0.67-3—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 7× in last 7d / 23× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. 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. Most recent first.

Showing the most recent 100 of 124 total refreshes for this CVE.

  1. 2026-08-21 23:44 UTCEPSS rescore
  2. 2026-08-20 22:51 UTCEPSS rescore
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Publicly available exploits

(1 reference)

Working exploit code is in the public domain (1 Exploit-DB entry). Defenders should treat patch urgency accordingly — public PoCs typically lead to mass-exploitation within 24-72 hours.

  • Exploit-DBEDB-42137✓ verified
    First seen Jun 7, 2017

    PuTTY < 0.68 - 'ssh_agent_channel_data' Integer Overflow Heap Corruption

    Open source ↗

Frequently asked(5)

What is CVE-2017-6542?
CVE-2017-6542 is a critical vulnerability published on March 27, 2017. The sshagentchannel_data function in PuTTY before 0.68 allows remote attackers to have unspecified impact via a large length value in an agent protocol message and leveraging the ability to connect to the Unix-domain socket representing the forwarded agent connection, which trigger a buffer…
When was CVE-2017-6542 disclosed?
CVE-2017-6542 was first published in the National Vulnerability Database on March 27, 2017, with the most recent update on June 17, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2017-6542 actively exploited?
CVE-2017-6542 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 22% probability of exploitation in the next 30 days, which ranks it in the top 2.5% of all scored CVEs.
What is the CVSS score of CVE-2017-6542?
CVE-2017-6542 has a CVSS v3 base score of 9.8 (NVD).
How do I remediate CVE-2017-6542?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2017-6542, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2017-6542

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