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HIGH

CVE-2026-81665

CVSS v3

7.5

HIGH

EPSS Score

0.3 %

exploit probability, as of 2026-09-28

CISA KEV

No

known exploited

Exploitation

—

SSVC status

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 potential

Technical details

Published
2026-09-04
Last Modified
2026-09-04

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 potential

Is CVE-2026-81665 actively exploited?

Active exploitation of CVE-2026-81665 has not been confirmed. Its EPSS score was 0.3% on 2026-09-28, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2026-81665?

CVE-2026-81665 has a CVSS v3 base score of 7.5 (HIGH severity).

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