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Vulnerability · Published Sep 4, 2026 · Assigned by redhat

CVE-2026-81665Corosync: corosync: heap-based buffer overflow in totempg assembly buffer during fragmented message reassembly

High 7.5

In plain English

A high-severity heap buffer overflow in Red Hat Enterprise Linux 10 from Red Hat. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 36% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)7.5High
Exploit odds (30 days)0.4%top 63.9% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official 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.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
AlmaLinux:10corosync3.1.10-1.el10_2.2ALSA-2026:67872
AlmaLinux:8corosync3.1.8-1.el8_10.2ALSA-2026:69277
AlmaLinux:9corosync3.1.10-1.el9_8.2ALSA-2026:67873
AlmaLinux:10corosync-vqsim3.1.10-1.el10_2.2ALSA-2026:67872
AlmaLinux:8corosync-vqsim3.1.8-1.el8_10.2ALSA-2026:69277
AlmaLinux:9corosync-vqsim3.1.10-1.el9_8.2ALSA-2026:67873
AlmaLinux:10corosynclib3.1.10-1.el10_2.2ALSA-2026:67872
AlmaLinux:8corosynclib3.1.8-1.el8_10.2ALSA-2026:69277
AlmaLinux:9corosynclib3.1.10-1.el9_8.2ALSA-2026:67873
AlmaLinux:10corosynclib-devel3.1.10-1.el10_2.2ALSA-2026:67872
AlmaLinux:8corosynclib-devel3.1.8-1.el8_10.2ALSA-2026:69277
AlmaLinux:9corosynclib-devel3.1.10-1.el9_8.2ALSA-2026:67873
AlmaLinux:8spausedd3.1.8-1.el8_10.2ALSA-2026:69277
Debian:12corosyncno fix listedDEBIAN-CVE-2026-81665
Debian:13corosyncno fix listedDEBIAN-CVE-2026-81665
Debian:14corosyncno fix listedDEBIAN-CVE-2026-81665
Rocky Linux:10corosync0:3.1.10-1.el10_2.2RLSA-2026:67872
Rocky Linux:8corosync0:3.1.8-1.el8_10.2RLSA-2026:69277
Rocky Linux:9corosync0:3.1.10-1.el9_8.2RLSA-2026:67873
Ubuntu:22.04:LTScorosyncno fix listedUBUNTU-CVE-2026-81665
Ubuntu:24.04:LTScorosyncno fix listedUBUNTU-CVE-2026-81665
Ubuntu:26.04:LTScorosyncno fix listedUBUNTU-CVE-2026-81665
Ubuntu:26.10corosyncno fix listedUBUNTU-CVE-2026-81665

Affected products (as reported)

VendorProductVersions
Red Hat Red Hat Enterprise Linux 10 see references
Red Hat Red Hat Enterprise Linux 10.0 Extended Update Support see references
Red Hat Red Hat Enterprise Linux 7 Extended Lifecycle Support see references
Red Hat Red Hat Enterprise Linux 8 see references
Red Hat Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support see references
Red Hat Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On see references
Red Hat Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support see references
Red Hat Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On see references
Red Hat Red Hat Enterprise Linux 8.8 Telecommunications Update Service see references
Red Hat Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions see references
Red Hat Red Hat Enterprise Linux 9 see references
Red Hat Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions see references
Red Hat Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions see references
Red Hat Red Hat Enterprise Linux 9.6 Extended Update Support see references
Red Hat Red Hat OpenShift Container Platform 4 see references
Red Hat Red Hat OpenShift Container Platform 4 see references
Red Hat Red Hat OpenShift Container Platform 5 see references
Red Hat Red Hat OpenShift Container Platform 5 see references

Weakness: CWE-122 · Vector: CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

References