Red Hat Enterprise Linux 10: Heap-based Buffer Overflow
CVE-2026-81665 is a high-severity heap-based buffer overflow vulnerability in Red Hat Enterprise Linux 10 from Red Hat, with a CVSS 3.1 base score of 7.5 out of 10. It can be exploited from the same local network by an unauthenticated attacker, without any action from a user. There is no confirmed exploitation so far. EPSS estimates a 0.42% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Check which version of Red Hat Enterprise Linux 10 you run against the affected versions below, and install the vendor's latest release.
Affected products and versions
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- AdjacentThe attacker must be on the same local network segment.
- Attack complexity
- HighSuccess depends on conditions outside the attacker's control.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H. Scored by CNA (redhat.com).
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.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Heap-based Buffer Overflow
The product writes past the end of a buffer that was allocated on the heap.
How developers prevent this class of flaw
- Pre-design: Use a language or compiler that performs automatic bounds checking.
- Use an abstraction library to abstract away risky APIs. Not a complete solution.
- Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index checking. D3-SFCV (Stack Frame Canary Validation) from D3FEND discusses canary-based detection in detail.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Other references
- access.redhat.com/errata/RHSA-2026:67872
- access.redhat.com/errata/RHSA-2026:67873
- access.redhat.com/errata/RHSA-2026:67878
- access.redhat.com/errata/RHSA-2026:67879
- access.redhat.com/errata/RHSA-2026:67880
- access.redhat.com/errata/RHSA-2026:67881
- access.redhat.com/errata/RHSA-2026:68574
- access.redhat.com/errata/RHSA-2026:69277
- access.redhat.com/errata/RHSA-2026:69278
- access.redhat.com/errata/RHSA-2026:69279
- access.redhat.com/errata/RHSA-2026:69280
- access.redhat.com/security/cve/CVE-2026-81665
- bugzilla.redhat.com/show_bug.cgi?id=2524910
Other vulnerabilities in Red Hat Enterprise Linux 10
- 8.8 High severity
- 7.5 High severity
- 7.5 High severity
- 7.9 High severity
- 7.3 High severity
- 7.5 High severity
Recent Heap-based Buffer Overflow vulnerabilities
- 7.8 High severity
- 8.1 High severity
- 8.8 High severity
- 8.2 High severity
- 7.1 High severity
- 9.3 Critical severity
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