CVE-2026-81665

HIGHCVSS 7.5/10EPSS 0.36%

Last modified

CVE-2026-81665 is a high-severity vulnerability rated 7.5/10 on the CVSS scale. 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. EPSS estimates a 0.36% chance of exploitation in the next 30 days.

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.

Metrics

EPSS Probability
0.36%

29.3th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

VendorProductVersions
Red HatRed Hat Enterprise Linux 10All versions
Red HatRed Hat Enterprise Linux 10.0 Extended Update SupportAll versions
Red HatRed Hat Enterprise Linux 7 Extended Lifecycle SupportAll versions
Red HatRed Hat Enterprise Linux 8All versions
Red HatRed Hat Enterprise Linux 8.4 Advanced Mission Critical Update SupportAll versions
Red HatRed Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-OnAll versions
Red HatRed Hat Enterprise Linux 8.6 Advanced Mission Critical Update SupportAll versions
Red HatRed Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-OnAll versions
Red HatRed Hat Enterprise Linux 8.8 Telecommunications Update ServiceAll versions
Red HatRed Hat Enterprise Linux 8.8 Update Services for SAP SolutionsAll versions
Red HatRed Hat Enterprise Linux 9All versions
Red HatRed Hat Enterprise Linux 9.2 Update Services for SAP SolutionsAll versions
Red HatRed Hat Enterprise Linux 9.4 Update Services for SAP SolutionsAll versions
Red HatRed Hat Enterprise Linux 9.6 Extended Update SupportAll versions
Red HatRed Hat OpenShift Container Platform 4All versions

References

Timeline

Published
Last Modified
Status
Awaiting Analysis

Frequently Asked Questions

What is CVE-2026-81665?
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.
How severe is CVE-2026-81665?
CVE-2026-81665 has a CVSS score of 7.5/10 (HIGH severity). The EPSS model estimates a 0.36% probability of exploitation in the next 30 days.
How do I fix CVE-2026-81665?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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Source: NVD / NIST