Bug 2461476 (CVE-2026-31659)

Summary: CVE-2026-31659 kernel: batman-adv: reject oversized global TT response buffers
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
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Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
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Hardware: All   
OS: Linux   
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A flaw was found in the batman-adv component of the Linux kernel. A remote attacker can exploit this vulnerability by sending a specially crafted oversized global Topology Table (TT) response. This causes an integer overflow during memory allocation, leading to a heap overflow and memory corruption. This memory corruption could potentially result in a denial of service or other unpredictable system behavior.
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Description OSIDB Bzimport 2026-04-24 15:03:42 UTC 
In the Linux kernel, the following vulnerability has been resolved:

batman-adv: reject oversized global TT response buffers

batadv_tt_prepare_tvlv_global_data() builds the allocation length for a
global TT response in 16-bit temporaries. When a remote originator
advertises a large enough global TT, the TT payload length plus the VLAN
header offset can exceed 65535 and wrap before kmalloc().

The full-table response path still uses the original TT payload length when
it fills tt_change, so the wrapped allocation is too small and
batadv_tt_prepare_tvlv_global_data() writes past the end of the heap object
before the later packet-size check runs.

Fix this by rejecting TT responses whose TVLV value length cannot fit in
the 16-bit TVLV payload length field.
Comment 1 Keith Grant 2026-04-24 22:14:13 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026042403-CVE-2026-31659-58eb@gregkh/T