CVE-2026-66034

HIGHPre-NVD 7.57.5—
EchelonGraph scoreMEDIUM confidence

Score 7.5 from GitHub Security Advisory (severity: HIGH) published 2026-07-24. a secondary CVSS source baseline 7.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 4 sources updated this week
7.5EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 7.5Exploit: None knownExposed: 0

A fix is available — apply it.

libssh2 through 1.11.1, fixed in commit a13bb6c, contains a missing bounds check vulnerability that allows a malicious SSH server to trigger an arbitrary-length heap out-of-bounds read and a free of an uninitialized pointer via the publickey subsystem. In libssh2_publickey_list_fetch(), the version 1 response parser reads a server-controlled comment_len value and advances the parse pointer without verifying sufficient bytes remain in the buffer, causing the out-of-bounds read to leak heap pointers from adjacent allocations defeating ASLR, followed by heap allocator state corruption when the error cleanup path frees an uninitialized pointer from a non-zeroed realloc() region.

CVSS v3
7.5
EG Score
7.5(medium)
EG Risk
34(Track)
EG Risk 34/100SSVC: 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
Severity75% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
34%
KEV
Not listed

Published

July 24, 2026

Last Modified

July 30, 2026

Advisory Details (3)

Auto-updated Jul 24, 2026
Upstream fix merged — awaiting tagged release. Sources: github_pr, github_commit.
generic

libssh2 Heap Out-of-Bounds Read via publickey subsystem | Advisories | VulnCheck

https://www.vulncheck.com/advisories/libssh2-heap-out-of-bounds-read-via-publickey-subsystem
github_commit

commit a13bb6c773f0 (libssh2/libssh2)

Fix landed in libssh2/libssh2 commit a13bb6c773f0 — awaiting tagged release

https://github.com/libssh2/libssh2/commit/a13bb6c773f0d55ad1628cede57e99803cd898d9
github_pr

publickey: fix potential OOB read in `libssh2_publickey_list_fetch()`

Upstream fix in progress (PR #2202 · libssh2/libssh2, state=closed)

https://github.com/libssh2/libssh2/pull/2202

Vendor Advisories for CVE-2026-66034(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 / EcosystemFixed in / PatchReleasedSource
redhatlibssh2-0:1.8.0-4.el7_9.22026-08-31redhat
redhatlibssh2-main-1.11.1-10.2.hum12026-07-27redhat

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

(4 across 4 ecosystems)
Debian:11(1)
PackageVulnerable rangeFixed inDependents
libssh21.10.0-1 ... 1.9.0-3 (20 versions)——
Debian:12(1)
PackageVulnerable rangeFixed inDependents
libssh21.10.0-31.10.0-3+deb12u1—
Debian:13(1)
PackageVulnerable rangeFixed inDependents
libssh21.11.1-1 ... 1.11.1-6 (7 versions)——
Debian:14(1)
PackageVulnerable rangeFixed inDependents
libssh21.11.1-1, 1.11.1-2, 1.11.1-3, 1.11.1-41.11.1-5—

Weakness Classification(2)

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

Additional Vendor Advisories

(1)

Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.

Data Freshness Timeline

(refreshed 30× in last 7d / 132× 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 276 total refreshes for this CVE.

  1. 2026-09-15 09:36 UTCEG score recompute
  2. 2026-09-15 09:36 UTCVendor advisory
  3. 2026-09-15 09:36 UTCGHSA enrichment
  4. 2026-09-14 16:06 UTCVendor advisory
  5. 2026-09-14 16:06 UTCGHSA enrichment
  6. 2026-09-14 02:56 UTCEG score recompute
  7. 2026-09-14 02:56 UTCVendor advisory
  8. 2026-09-14 02:56 UTCGHSA enrichment
  9. 2026-09-13 15:29 UTCVendor advisory
  10. 2026-09-13 15:29 UTCGHSA enrichment
  11. 2026-09-13 04:02 UTCVendor advisory
  12. 2026-09-13 04:02 UTCGHSA enrichment
  13. 2026-09-12 16:35 UTCEG score recompute
  14. 2026-09-12 16:35 UTCVendor advisory
  15. 2026-09-12 16:35 UTCGHSA enrichment
  16. 2026-09-12 05:05 UTCVendor advisory
  17. 2026-09-12 05:04 UTCGHSA enrichment
  18. 2026-09-11 16:36 UTCEG score recompute
  19. 2026-09-11 16:36 UTCVendor advisory
  20. 2026-09-11 16:36 UTCGHSA enrichment
  21. 2026-09-11 14:53 UTCEPSS rescore
  22. 2026-09-11 09:37 UTCEPSS rescore
  23. 2026-09-11 02:34 UTCVendor advisory
  24. 2026-09-11 02:34 UTCGHSA enrichment
  25. 2026-09-10 13:35 UTCEG score recompute
Show 75 more
  1. 2026-09-10 13:35 UTCVendor advisory
  2. 2026-09-10 13:35 UTCGHSA enrichment
  3. 2026-09-09 08:45 UTCEG score recompute
  4. 2026-09-09 08:45 UTCVendor advisory
  5. 2026-09-09 08:45 UTCGHSA enrichment
  6. 2026-09-08 22:01 UTCEPSS rescore
  7. 2026-09-07 21:23 UTCEG score recompute
  8. 2026-09-07 21:23 UTCVendor advisory
  9. 2026-09-07 21:23 UTCGHSA enrichment
  10. 2026-09-07 16:01 UTCEPSS rescore
  11. 2026-09-06 13:47 UTCEPSS rescore
  12. 2026-09-06 08:10 UTCVendor advisory
  13. 2026-09-06 08:10 UTCGHSA enrichment
  14. 2026-09-05 19:23 UTCEG score recompute
  15. 2026-09-05 19:23 UTCVendor advisory
  16. 2026-09-05 19:23 UTCGHSA enrichment
  17. 2026-09-05 15:31 UTCEPSS rescore
  18. 2026-09-05 06:53 UTCEG score recompute
  19. 2026-09-05 06:53 UTCVendor advisory
  20. 2026-09-05 06:53 UTCGHSA enrichment
  21. 2026-09-04 12:49 UTCEG score recompute
  22. 2026-09-04 12:49 UTCVendor advisory
  23. 2026-09-04 12:48 UTCGHSA enrichment
  24. 2026-09-04 05:07 UTCEPSS rescore
  25. 2026-09-02 14:12 UTCEPSS rescore
  26. 2026-09-01 23:16 UTCEG score recompute
  27. 2026-09-01 23:16 UTCVendor advisory
  28. 2026-09-01 23:16 UTCGHSA enrichment
  29. 2026-09-01 13:54 UTCEPSS rescore
  30. 2026-09-01 04:40 UTCEPSS rescore
  31. 2026-08-30 23:11 UTCEG score recompute
  32. 2026-08-30 23:11 UTCVendor advisory
  33. 2026-08-30 23:11 UTCGHSA enrichment
  34. 2026-08-30 19:17 UTCEPSS rescore
  35. 2026-08-30 11:44 UTCEG score recompute
  36. 2026-08-30 11:44 UTCVendor advisory
  37. 2026-08-30 11:44 UTCGHSA enrichment
  38. 2026-08-30 01:22 UTCEPSS rescore
  39. 2026-08-30 00:16 UTCEG score recompute
  40. 2026-08-30 00:16 UTCVendor advisory
  41. 2026-08-30 00:16 UTCGHSA enrichment
  42. 2026-08-28 21:42 UTCEPSS rescore
  43. 2026-08-27 23:09 UTCEG score recompute
  44. 2026-08-27 23:09 UTCVendor advisory
  45. 2026-08-27 23:08 UTCGHSA enrichment
  46. 2026-08-27 11:41 UTCVendor advisory
  47. 2026-08-27 11:41 UTCGHSA enrichment
  48. 2026-08-27 00:14 UTCEG score recompute
  49. 2026-08-27 00:14 UTCVendor advisory
  50. 2026-08-27 00:14 UTCGHSA enrichment
  51. 2026-08-26 14:47 UTCEPSS rescore
  52. 2026-08-26 12:47 UTCVendor advisory
  53. 2026-08-26 12:46 UTCGHSA enrichment
  54. 2026-08-26 01:19 UTCVendor advisory
  55. 2026-08-26 01:19 UTCGHSA enrichment
  56. 2026-08-25 13:51 UTCEG score recompute
  57. 2026-08-25 13:51 UTCVendor advisory
  58. 2026-08-25 13:51 UTCGHSA enrichment
  59. 2026-08-25 13:49 UTCEPSS rescore
  60. 2026-08-25 02:23 UTCVendor advisory
  61. 2026-08-25 02:23 UTCGHSA enrichment
  62. 2026-08-24 14:56 UTCEG score recompute
  63. 2026-08-24 14:56 UTCVendor advisory
  64. 2026-08-24 14:56 UTCGHSA enrichment
  65. 2026-08-24 03:28 UTCEG score recompute
  66. 2026-08-24 03:28 UTCVendor advisory
  67. 2026-08-24 03:28 UTCGHSA enrichment
  68. 2026-08-23 15:55 UTCVendor advisory
  69. 2026-08-23 15:55 UTCGHSA enrichment
  70. 2026-08-23 04:27 UTCEG score recompute
  71. 2026-08-23 04:27 UTCVendor advisory
  72. 2026-08-23 04:27 UTCGHSA enrichment
  73. 2026-08-23 00:19 UTCEPSS rescore
  74. 2026-08-22 17:01 UTCVendor advisory
  75. 2026-08-22 17:01 UTCGHSA enrichment

Related CVEs(same vendor + same CWE)

Frequently asked(5)

What is CVE-2026-66034?
CVE-2026-66034 is a high vulnerability published on July 24, 2026. libssh2 through 1.11.1, fixed in commit a13bb6c, contains a missing bounds check vulnerability that allows a malicious SSH server to trigger an arbitrary-length heap out-of-bounds read and a free of an uninitialized pointer via the publickey subsystem. In libssh2publickeylistfetch(), the version 1…
When was CVE-2026-66034 disclosed?
CVE-2026-66034 was first published in the National Vulnerability Database on July 24, 2026, with the most recent update on July 30, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-66034 actively exploited?
CVE-2026-66034 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 66.2% of all scored CVEs.
What is the CVSS score of CVE-2026-66034?
CVE-2026-66034 has a CVSS v3 base score of 7.5 (NVD).
How do I remediate CVE-2026-66034?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-66034, 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

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