Bug 2396919 (CVE-2025-39839)

Summary: CVE-2025-39839 kernel: batman-adv: fix OOB read/write in network-coding decode
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Version: unspecifiedKeywords: Security
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OS: Linux   
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Description OSIDB Bzimport 2025-09-19 16:01:33 UTC 
In the Linux kernel, the following vulnerability has been resolved:

batman-adv: fix OOB read/write in network-coding decode

batadv_nc_skb_decode_packet() trusts coded_len and checks only against
skb->len. XOR starts at sizeof(struct batadv_unicast_packet), reducing
payload headroom, and the source skb length is not verified, allowing an
out-of-bounds read and a small out-of-bounds write.

Validate that coded_len fits within the payload area of both destination
and source sk_buffs before XORing.
Comment 1 Jon Moroney 2025-09-19 17:25:21 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2025091902-CVE-2025-39839-2786@gregkh/T