CVE-2026-81665

7.5 HIGH 0.4% exploit odds No fix listed Memory safety

What it is

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.

At a glance

Exploitability: Can be exploited from the same network segment without logging in. High risk of data exposure, data tampering, service disruption.
Exploit odds: 0.4% chance of exploitation in the next 30 days (EPSS).
Fix: No patch or advisory is linked yet. Look at mitigations or restrict exposure.

Timeline

2026-08-27 10:38 UTC ReservedThe CVE id was reserved by its CNA
2026-09-04 09:17 UTC PublishedDisclosed publicly on CVE.org and NVD
2026-11-02 16:17 UTC Last updatedMost recent change to the record

Why it ranks here

Exploited in the wild: no, CISA does not list it.
Exploit odds: 0.4% in the next 30 days (EPSS).
Severity: 7.5 HIGH (CVSS).
Fix: none linked yet, which raises it.

Details

Published: 2026-09-04 09:17 UTC
Last modified: 2026-11-02 16:17 UTC
Exploit probability: 0.4% · EPSS, next 30 days
Weakness: CWE-122
Record status: Awaiting Analysis

Attack profile CVSS 3.1 · 7.5

Attack vector: Adjacent network
Complexity: High
Privileges needed: None
User interaction: None
Scope: Unchanged
Confidentiality: High
Integrity: High
Availability: High

Raw vector

CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Is it in your code?

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References

NVD record · CVE.org record