CVE-2026-81665

HIGHPre-NVD 7.57.5—
EchelonGraph scoreHIGH confidence

Score 7.5 from GitHub Security Advisory (severity: HIGH) published 2026-09-04. a secondary CVSS source baseline 7.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — Patch released 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.

A heap-based buffer overflow was found in Corosync's Totem Process Group (totempg) message reassembly. When processing fragmented multicast messages, the buffer used to reassemble fragments lacks a runtime bounds check in release builds. A network-adjacent attacker able to send crafted multicast protocol messages to the cluster could cause a heap buffer overflow with attacker-controlled data. This can crash the Corosync daemon, causing a denial of service to the entire cluster, and may potentially allow further exploitation given sufficient heap-corruption control.

CVSS v3
7.5
EG Score
7.5(high)
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
26%
KEV
Not listed

Published

September 4, 2026

Last Modified

September 18, 2026

Advisory Details (1)

Auto-updated Sep 4, 2026
No patch confirmed yet. Sources: redhat.
redhat

2524910 – (CVE-2026-81665) CVE-2026-81665 corosync: corosync: heap-based buffer overflow in totempg assembly buffer during fragmented message reassembly

https://bugzilla.redhat.com/show_bug.cgi?id=2524910

Vendor Advisories for CVE-2026-81665(6)

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

Patch Availability(7)

Vendor / EcosystemFixed in / PatchReleasedSource
redhatcorosync-0:3.1.7-1.el9_2.22026-09-18redhat
redhatcorosync-0:2.4.5-7.el7_9.42026-09-17redhat
redhatcorosync-0:3.1.8-1.el9_4.22026-09-16redhat
redhatcorosync-0:3.1.9-1.el10_0.32026-09-16redhat
redhatcorosync-0:3.1.10-1.el10_2.22026-09-16redhat
redhatcorosync-0:3.1.9-2.el9_6.22026-09-16redhat
redhatcorosync-0:3.1.10-1.el9_8.22026-09-16redhat

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

(3 across 3 ecosystems)
Debian:12(1)
PackageVulnerable rangeFixed inDependents
corosync3.1.10-1 ... 3.1.9-2 (12 versions)——
Debian:13(1)
PackageVulnerable rangeFixed inDependents
corosync3.1.10-1 ... 3.1.9-2+deb13u1 (6 versions)——
Debian:14(1)
PackageVulnerable rangeFixed inDependents
corosync3.1.10-1, 3.1.10-2, 3.1.10-3, 3.1.10-4, 3.1.9-2——

Weakness Classification(1)

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

Additional Vendor Advisories

(2)

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 43× in last 7d / 75× 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. 2026-09-19 01:25 UTCEG score recompute
  2. 2026-09-19 01:25 UTCVendor advisory
  3. 2026-09-19 01:25 UTCGHSA enrichment
  4. 2026-09-18 19:28 UTCEPSS rescore
  5. 2026-09-18 12:22 UTCEG score recompute
  6. 2026-09-18 12:22 UTCVendor advisory
  7. 2026-09-18 12:22 UTCGHSA enrichment
  8. 2026-09-18 11:29 UTCEG score recompute
  9. 2026-09-18 11:29 UTCVendor advisory
  10. 2026-09-18 11:29 UTCGHSA enrichment
  11. 2026-09-18 01:23 UTCEG score recompute
  12. 2026-09-18 01:23 UTCVendor advisory
  13. 2026-09-18 01:23 UTCGHSA enrichment
  14. 2026-09-17 12:20 UTCEG score recompute
  15. 2026-09-17 12:20 UTCVendor advisory
  16. 2026-09-17 12:20 UTCGHSA enrichment
  17. 2026-09-17 11:49 UTCEG score recompute
  18. 2026-09-17 11:49 UTCGHSA enrichment
  19. 2026-09-17 03:28 UTCGHSA enrichment
  20. 2026-09-16 14:25 UTCEG score recompute
  21. 2026-09-16 14:25 UTCGHSA enrichment
  22. 2026-09-16 14:08 UTCEPSS rescore
  23. 2026-09-16 13:37 UTCGHSA enrichment
  24. 2026-09-16 12:46 UTCEG score recompute
  25. 2026-09-16 12:46 UTCGHSA enrichment
Show 50 more
  1. 2026-09-16 12:22 UTCEG score recompute
  2. 2026-09-16 12:22 UTCGHSA enrichment
  3. 2026-09-16 11:56 UTCGHSA enrichment
  4. 2026-09-16 11:21 UTCEG score recompute
  5. 2026-09-16 11:21 UTCGHSA enrichment
  6. 2026-09-16 05:15 UTCEPSS rescore
  7. 2026-09-15 23:24 UTCGHSA enrichment
  8. 2026-09-15 09:53 UTCEG score recompute
  9. 2026-09-15 09:53 UTCGHSA enrichment
  10. 2026-09-15 03:12 UTCEPSS rescore
  11. 2026-09-15 03:12 UTCEPSS rescore
  12. 2026-09-14 20:50 UTCGHSA enrichment
  13. 2026-09-14 07:48 UTCGHSA enrichment
  14. 2026-09-13 18:45 UTCEG score recompute
  15. 2026-09-13 18:45 UTCGHSA enrichment
  16. 2026-09-13 05:42 UTCGHSA enrichment
  17. 2026-09-12 16:40 UTCEG score recompute
  18. 2026-09-12 16:40 UTCGHSA enrichment
  19. 2026-09-12 03:38 UTCEG score recompute
  20. 2026-09-12 03:38 UTCGHSA enrichment
  21. 2026-09-11 14:53 UTCEPSS rescore
  22. 2026-09-11 14:53 UTCEPSS rescore
  23. 2026-09-11 14:35 UTCEG score recompute
  24. 2026-09-11 14:35 UTCGHSA enrichment
  25. 2026-09-11 01:32 UTCGHSA enrichment
  26. 2026-09-10 12:29 UTCEG score recompute
  27. 2026-09-10 12:29 UTCGHSA enrichment
  28. 2026-09-09 23:24 UTCGHSA enrichment
  29. 2026-09-09 09:01 UTCEG score recompute
  30. 2026-09-09 09:01 UTCGHSA enrichment
  31. 2026-09-08 22:01 UTCEPSS rescore
  32. 2026-09-08 19:58 UTCGHSA enrichment
  33. 2026-09-08 03:50 UTCEG score recompute
  34. 2026-09-08 03:50 UTCGHSA enrichment
  35. 2026-09-07 14:47 UTCGHSA enrichment
  36. 2026-09-06 23:30 UTCEG score recompute
  37. 2026-09-06 23:30 UTCGHSA enrichment
  38. 2026-09-06 13:48 UTCEPSS rescore
  39. 2026-09-06 10:27 UTCGHSA enrichment
  40. 2026-09-05 21:24 UTCEG score recompute
  41. 2026-09-05 21:24 UTCGHSA enrichment
  42. 2026-09-05 15:31 UTCEPSS rescore
  43. 2026-09-05 08:22 UTCGHSA enrichment
  44. 2026-09-04 19:19 UTCEG score recompute
  45. 2026-09-04 19:19 UTCGHSA enrichment
  46. 2026-09-04 18:41 UTCEG score recompute
  47. 2026-09-04 18:40 UTCGHSA enrichment
  48. 2026-09-04 09:30 UTCEG score recompute
  49. 2026-09-04 09:09 UTCEG score recompute
  50. 2026-09-04 09:08 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-81665?
CVE-2026-81665 is a high vulnerability published on September 4, 2026. A heap-based buffer overflow was found in Corosync's Totem Process Group (totempg) message reassembly. When processing fragmented multicast messages, the buffer used to reassemble fragments lacks a runtime bounds check in release builds. A network-adjacent attacker able to send crafted multicast…
When was CVE-2026-81665 disclosed?
CVE-2026-81665 was first published in the National Vulnerability Database on September 4, 2026, with the most recent update on September 18, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-81665 actively exploited?
CVE-2026-81665 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 74.4% of all scored CVEs.
What is the CVSS score of CVE-2026-81665?
CVE-2026-81665 has a CVSS v3 base score of 7.5 (NVD).
How do I remediate CVE-2026-81665?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-81665, 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-2026-81665

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