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
9.8
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 22%CVSS: 9.8Exploit: NoneExposed: 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)
EPSS
97.3%
KEV
Not listed

Published

March 27, 2017

Last Modified

May 13, 2026

Advisory Details (6)

Auto-updated Jun 21, 2026
🔬 Proof of concept available. No patch confirmed yet.
generic🟡 PoC Available

PuTTY vulnerability vuln-agent-fwd-overflow

http://www.chiark.greenend.org.uk/~sgtatham/putty/wishlist/vuln-agent-fwd-overflow.html
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
http://www.securityfocus.com/bid/97156
generic🟡 PoC Available

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

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

Data Freshness Timeline

(refreshed 8× in last 7d / 36× 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.

  1. 2026-07-06 16:24 UTCEPSS rescore
  2. 2026-07-06 16:24 UTCEPSS rescore
  3. 2026-07-05 02:27 UTCEPSS rescore
  4. 2026-07-04 06:28 UTCEPSS rescore
  5. 2026-07-02 16:54 UTCEPSS rescore
  6. 2026-07-01 15:02 UTCEPSS rescore
  7. 2026-06-30 23:19 UTCEPSS rescore
  8. 2026-06-30 23:19 UTCEPSS rescore
  9. 2026-06-29 14:03 UTCEPSS rescore
  10. 2026-06-28 14:04 UTCEPSS rescore
  11. 2026-06-28 04:53 UTCEPSS rescore
  12. 2026-06-27 03:06 UTCEPSS rescore
  13. 2026-06-27 03:05 UTCEPSS rescore
  14. 2026-06-25 13:47 UTCEPSS rescore
  15. 2026-06-24 14:02 UTCEPSS rescore
  16. 2026-06-24 14:02 UTCEPSS rescore
  17. 2026-06-23 21:30 UTCEPSS rescore
  18. 2026-06-22 14:23 UTCEPSS rescore
  19. 2026-06-22 14:23 UTCEPSS rescore
  20. 2026-06-21 01:57 UTCEPSS rescore
  21. 2026-06-21 01:57 UTCEPSS rescore
  22. 2026-06-19 23:06 UTCOSV refresh
  23. 2026-06-19 19:23 UTCEPSS rescore
  24. 2026-06-19 19:23 UTCEPSS rescore
  25. 2026-06-18 17:50 UTCEPSS rescore
Show 62 more
  1. 2026-06-17 17:50 UTCEPSS rescore
  2. 2026-06-16 17:50 UTCEPSS rescore
  3. 2026-06-16 17:50 UTCEPSS rescore
  4. 2026-06-15 17:45 UTCEPSS rescore
  5. 2026-06-14 23:14 UTCEPSS rescore
  6. 2026-06-13 22:57 UTCEPSS rescore
  7. 2026-06-12 23:09 UTCEPSS rescore
  8. 2026-06-10 22:15 UTCEPSS rescore
  9. 2026-06-10 13:19 UTCEPSS rescore
  10. 2026-06-08 14:14 UTCEPSS rescore
  11. 2026-06-08 14:14 UTCEPSS rescore
  12. 2026-06-06 13:45 UTCEPSS rescore
  13. 2026-06-06 13:45 UTCEPSS rescore
  14. 2026-06-05 22:44 UTCEPSS rescore
  15. 2026-06-05 06:08 UTCEPSS rescore
  16. 2026-06-05 06:08 UTCEPSS rescore
  17. 2026-06-04 13:10 UTCEPSS rescore
  18. 2026-06-02 20:11 UTCEPSS rescore
  19. 2026-06-02 20:11 UTCEPSS rescore
  20. 2026-06-01 13:49 UTCEPSS rescore
  21. 2026-05-31 22:28 UTCEPSS rescore
  22. 2026-05-31 22:28 UTCEPSS rescore
  23. 2026-05-31 01:55 UTCOSV refresh
  24. 2026-05-29 13:41 UTCEPSS rescore
  25. 2026-05-28 13:42 UTCEPSS rescore
  26. 2026-05-28 13:42 UTCEPSS rescore
  27. 2026-05-27 13:38 UTCEPSS rescore
  28. 2026-05-27 13:38 UTCEPSS rescore
  29. 2026-05-26 13:42 UTCEPSS rescore
  30. 2026-05-26 13:42 UTCEPSS rescore
  31. 2026-05-26 07:17 UTCEPSS rescore
  32. 2026-05-26 07:17 UTCEPSS rescore
  33. 2026-05-22 21:15 UTCEPSS rescore
  34. 2026-05-22 21:15 UTCEPSS rescore
  35. 2026-05-22 21:15 UTCEPSS rescore
  36. 2026-05-22 21:15 UTCEPSS rescore
  37. 2026-05-22 21:15 UTCEPSS rescore
  38. 2026-05-21 22:40 UTCEPSS rescore
  39. 2026-05-20 22:37 UTCEPSS rescore
  40. 2026-05-20 22:37 UTCEPSS rescore
  41. 2026-05-20 22:37 UTCEPSS rescore
  42. 2026-05-20 11:21 UTCEPSS rescore
  43. 2026-05-20 11:21 UTCEPSS rescore
  44. 2026-05-20 10:20 UTCEG score recompute
  45. 2026-05-20 10:20 UTCGHSA enrichment
  46. 2026-05-20 06:04 UTCEG score recompute
  47. 2026-05-20 06:04 UTCGHSA enrichment
  48. 2026-05-20 01:48 UTCEG score recompute
  49. 2026-05-20 01:48 UTCGHSA enrichment
  50. 2026-05-19 21:32 UTCEG score recompute
  51. 2026-05-19 21:32 UTCGHSA enrichment
  52. 2026-05-19 17:16 UTCEG score recompute
  53. 2026-05-19 17:16 UTCGHSA enrichment
  54. 2026-05-19 13:00 UTCEG score recompute
  55. 2026-05-19 13:00 UTCGHSA enrichment
  56. 2026-05-19 08:44 UTCEG score recompute
  57. 2026-05-19 08:44 UTCGHSA enrichment
  58. 2026-05-19 04:28 UTCEG score recompute
  59. 2026-05-19 04:28 UTCGHSA enrichment
  60. 2026-05-19 00:13 UTCEG score recompute
  61. 2026-05-19 00:12 UTCGHSA enrichment
  62. 2026-05-18 21:30 UTCEPSS rescore

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 May 13, 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 97.3% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
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.

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