Bug 2461756 (CVE-2026-31683)

Summary: CVE-2026-31683 kernel: batman-adv: avoid OGM aggregation when skb tailroom is insufficient
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: unspecified Docs Contact:
Priority: unspecified    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in the batman-adv module of the Linux kernel. This vulnerability arises when the Optimized Global Messaging (OGM) aggregation state is dynamically altered, leading to insufficient buffer space (skb tailroom) for network packets. A remote attacker could exploit this condition by sending specially crafted network packets, potentially causing a memory corruption vulnerability that results in a system crash or denial of service. The system may become unstable or unresponsive.
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Description OSIDB Bzimport 2026-04-25 09:01:30 UTC 
In the Linux kernel, the following vulnerability has been resolved:

batman-adv: avoid OGM aggregation when skb tailroom is insufficient

When OGM aggregation state is toggled at runtime, an existing forwarded
packet may have been allocated with only packet_len bytes, while a later
packet can still be selected for aggregation. Appending in this case can
hit skb_put overflow conditions.

Reject aggregation when the target skb tailroom cannot accommodate the new
packet. The caller then falls back to creating a new forward packet
instead of appending.
Comment 1 Alexander B 2026-04-27 10:12:20 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026042545-CVE-2026-31683-b833@gregkh/T