CVE-2026-81665
Corosync: corosync: heap-based buffer overflow in totempg assembly buffer during fragmented message reassembly
CVSS Score
7.5
EPSS Score
0.3%
EPSS Percentile
26th
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.
| CWE | CWE-122 |
| Vendor | red hat |
| Product | red hat enterprise linux 10 |
| Published | Sep 4, 2026 |
| Last Updated | Sep 30, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H Attack Vector
Adjacent
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High
Affected Versions
Red Hat / Red Hat Enterprise Linux 10
All versions affected Red Hat / Red Hat Enterprise Linux 10.0 Extended Update Support
All versions affected Red Hat / Red Hat Enterprise Linux 7 Extended Lifecycle Support
All versions affected Red Hat / Red Hat Enterprise Linux 8
All versions affected Red Hat / Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support
All versions affected Red Hat / Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On
All versions affected Red Hat / Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support
All versions affected Red Hat / Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On
All versions affected Red Hat / Red Hat Enterprise Linux 8.8 Telecommunications Update Service
All versions affected Red Hat / Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions
All versions affected Red Hat / Red Hat Enterprise Linux 9
All versions affected Red Hat / Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions
All versions affected Red Hat / Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions
All versions affected Red Hat / Red Hat Enterprise Linux 9.6 Extended Update Support
All versions affected Red Hat / Red Hat OpenShift Container Platform 4
All versions affected Red Hat / Red Hat OpenShift Container Platform 4
All versions affected References
access.redhat.com: https://access.redhat.com/errata/RHSA-2026:67872 access.redhat.com: https://access.redhat.com/errata/RHSA-2026:67873 access.redhat.com: https://access.redhat.com/errata/RHSA-2026:67878 access.redhat.com: https://access.redhat.com/errata/RHSA-2026:67879 access.redhat.com: https://access.redhat.com/errata/RHSA-2026:67880 access.redhat.com: https://access.redhat.com/errata/RHSA-2026:67881 access.redhat.com: https://access.redhat.com/errata/RHSA-2026:68574 access.redhat.com: https://access.redhat.com/errata/RHSA-2026:69277 access.redhat.com: https://access.redhat.com/errata/RHSA-2026:69278 access.redhat.com: https://access.redhat.com/errata/RHSA-2026:69279 access.redhat.com: https://access.redhat.com/errata/RHSA-2026:69280 access.redhat.com: https://access.redhat.com/security/cve/CVE-2026-81665 bugzilla.redhat.com: https://bugzilla.redhat.com/show_bug.cgi?id=2524910
Credits
Red Hat would like to thank Tristan Madani (Talence Security) for reporting this issue.