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Fencer Intel
medium 6.5

CVE-2026-81666 json

Corosync: corosync: integer overflow in check_memb_commit_token_sanity may bypass message length validation on 32-bit systems

published 2mo ago modified 6d ago also EUVD-2026-70987

cvss
6.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 16%
public exploits
0
none known

Summary

An integer overflow was found in Corosync's handling of membership commit token messages. The length-validation check for these messages can be bypassed on 32-bit systems due to an integer overflow in the calculation of the expected message length, allowing a crafted network packet to trigger an out-of-bounds memory access that crashes the Corosync daemon. This results in a denial of service for the affected cluster node. The overflow does not occur on 64-bit systems, where the length calculation is correctly performed in 64-bit arithmetic.

Patch / fix

  • corosync SLE High Availability Extension 16.0 3.1.9-160000.4.1
  • corosync SLE High Availability Extension 15 SP7, SLE High Availability Extension 15 SP6, SLE High Availability Extension 15 SP5 +1 more 2.4.6-150300.12.19.1

suse advisories SUSE-SU-2026:23850-1SUSE-SU-2026:4202-1

  • corosync openSUSE Leap 16.0 3.1.9-160000.4.1
  • corosync openSUSE Tumbleweed 3.1.10-5.1

opensuse advisories openSUSE-SU-2026:21887-1openSUSE-SU-2026:11715-1

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Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-81666 updated cvss 6.5

corosync: corosync: integer overflow in check_memb_commit_token_sanity may bypass message length validation on 32-bit systems

  • Red Hat Enterprise Linux 7 corosync, spausedd, corosynclib, corosync-qnetd, corosync-qdevice, corosync 3.1.10-1.el10_2.2 Red Hat Enterprise Linux 8 corosync, spausedd, corosynclib, corosync-vqsim, corosync 3.1.10-1.el10_2.2 Red Hat Enterprise Linux 9 corosync, corosynclib, corosync-vqsim, corosync 3.1.10-1.el10_2.2 Red Hat Enterprise Linux 10 corosync 3.1.10-1.el10_2.2 Red Hat OpenShift Container Platform 4 rhcos, openshift/ose-rhel-coreos-9 Red Hat OpenShift Container Platform 5 openshift/ose-rhel-coreos-9
    affected: workaround, no fix available “Fix deferred”

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
2mo ago

Exploit prediction

0.25% chance of exploitation in the next 30 days, higher than 16% of all scored CVEs (FIRST EPSS, 2026-11-11).

CVSS scores

assigned by version score vector
CNA 3.1 6.5 CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected products

  • Red Hat Red Hat Enterprise Linux 10
  • Red Hat Red Hat Enterprise Linux 7
  • Red Hat Red Hat Enterprise Linux 8
  • Red Hat Red Hat Enterprise Linux 9
  • Red Hat Red Hat OpenShift Container Platform 4
  • Red Hat Red Hat OpenShift Container Platform 5

Classification

Weakness
  • CWE-190 Integer Overflow or Wraparound

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.