CVE-2026-81665

HIGH
MEDIUM Priority: 0.03 BB Relevance: 50/100
Published: 2026-09-04 Modified: 2026-11-02 First seen: 2026-11-02 Status: active

Attack Surface

Adjacent No Auth No Interaction Conf. Impact Integ. Impact

CVSS Vector Breakdown

AV: Adjacent
AC: High
PR: None
UI: None
S: Unchanged
C: High
I: High
A: High

Description

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.

Weakness Classification (1)

References & Advisories (13)

https://access.redhat.com/errata/RHSA-2026:67872
vendor-advisory x_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:67873
vendor-advisory x_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:67878
vendor-advisory x_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:67879
vendor-advisory x_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:67880
vendor-advisory x_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:67881
vendor-advisory x_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:68574
vendor-advisory x_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:69277
vendor-advisory x_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:69278
vendor-advisory x_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:69279
vendor-advisory x_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:69280
vendor-advisory x_refsource_REDHAT
https://bugzilla.redhat.com/show_bug.cgi?id=2524910
issue-tracking x_refsource_REDHAT

Bug Bounty Relevance

50 / 100
✓ No authentication
✓ No user interaction

CVSS Score

7.5 / 10.0 v3.1
CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS — Exploitation Probability

0.42%
Raw Score 0.004160
Percentile 36.4%
Date 2026-11-13

EPSS Trend

2026-11-13
0.00416
2026-11-12
0.00416
2026-11-10
0.00416
2026-11-09
0.00416
2026-11-08
0.00416
2026-11-07
0.00416
2026-11-06
0.00416
2026-11-05
0.00416
2026-11-04
0.00416
2026-11-03
0.00416
2026-11-02
0.00416

Intelligence Sources

mitre ref →
nvd ref →