{"id":"CVE-2026-80839","state":"PUBLISHED","title":"batman-adv: reject unrepresentable multicast TVLV offsets","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nbatman-adv: reject unrepresentable multicast TVLV offsets\n\nThe network and transport header fields in struct sk_buff are 16-bit\noffsets from skb->head, and U16_MAX is reserved as the unset transport\nheader value. batadv_tvlv_call_handler() sets both fields from a received\nmulticast TVLV without checking whether the TVLV end is representable.\n\nIf the end offset exceeds the field's range, skb_set_transport_header()\ntruncates it so that the transport header precedes the network header.\nThe negative difference is then returned by skb_network_header_len() as\na large u32. batadv_mcast_forw_packet() consequently accepts an oversized\nmulticast tracker and accesses memory beyond the skb data.\n\nAdd skb_set_transport_header_careful(), an offset-aware counterpart to\nskb_reset_transport_header_careful(), which validates the final\nhead-relative offset before assigning it. Use the new helper in\nbatadv_tvlv_call_handler() and reject unrepresentable TVLVs before\nsetting the network header.","publishedAt":"2026-09-04T15:54:49.378Z","updatedAt":"2026-10-19T08:44:32.478Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"07afe1ba288c04280622fa002ed385f1ac0b6fe6","status":"affected","lessThan":"da1f5aa7ec93f2cc17f5cd30efc54f62af433cf2","versionType":"git"},{"version":"07afe1ba288c04280622fa002ed385f1ac0b6fe6","status":"affected","lessThan":"916ec741e65af072b98e475feaad98c063da1b7c","versionType":"git"},{"version":"07afe1ba288c04280622fa002ed385f1ac0b6fe6","status":"affected","lessThan":"1b466746fe109127fd983100a228cdd1f1f6ece2","versionType":"git"},{"version":"07afe1ba288c04280622fa002ed385f1ac0b6fe6","status":"affected","lessThan":"2b46baa591d0a7c16b62f150917187e70d053be6","versionType":"git"},{"version":"07afe1ba288c04280622fa002ed385f1ac0b6fe6","status":"affected","lessThan":"f12c2de4f542e3220e17e0606f492110064f04cb","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["include/linux/skbuff.h","net/batman-adv/tvlv.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.8","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.8","versionType":"semver"},{"version":"6.12.108","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.49","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.13","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2.3","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["include/linux/skbuff.h","net/batman-adv/tvlv.c"]}],"references":["https://git.kernel.org/stable/c/da1f5aa7ec93f2cc17f5cd30efc54f62af433cf2","https://git.kernel.org/stable/c/916ec741e65af072b98e475feaad98c063da1b7c","https://git.kernel.org/stable/c/1b466746fe109127fd983100a228cdd1f1f6ece2","https://git.kernel.org/stable/c/2b46baa591d0a7c16b62f150917187e70d053be6","https://git.kernel.org/stable/c/f12c2de4f542e3220e17e0606f492110064f04cb"],"weaknesses":[],"ingestedAt":"2026-10-29T20:13:07.220Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/80xxx/CVE-2026-80839.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-80839","state":"PUBLISHED","datePublished":"2026-09-04T15:54:49.378Z","dateUpdated":"2026-10-19T08:44:32.478Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-08-26T14:34:25.796Z"},"containers":{"cna":{"title":"batman-adv: reject unrepresentable multicast TVLV offsets","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nbatman-adv: reject unrepresentable multicast TVLV offsets\n\nThe network and transport header fields in struct sk_buff are 16-bit\noffsets from skb->head, and U16_MAX is reserved as the unset transport\nheader value. batadv_tvlv_call_handler() sets both fields from a received\nmulticast TVLV without checking whether the TVLV end is representable.\n\nIf the end offset exceeds the field's range, skb_set_transport_header()\ntruncates it so that the transport header precedes the network header.\nThe negative difference is then returned by skb_network_header_len() as\na large u32. batadv_mcast_forw_packet() consequently accepts an oversized\nmulticast tracker and accesses memory beyond the skb data.\n\nAdd skb_set_transport_header_careful(), an offset-aware counterpart to\nskb_reset_transport_header_careful(), which validates the final\nhead-relative offset before assigning it. Use the new helper in\nbatadv_tvlv_call_handler() and reject unrepresentable TVLVs before\nsetting the network header."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"07afe1ba288c04280622fa002ed385f1ac0b6fe6","status":"affected","lessThan":"da1f5aa7ec93f2cc17f5cd30efc54f62af433cf2","versionType":"git"},{"version":"07afe1ba288c04280622fa002ed385f1ac0b6fe6","status":"affected","lessThan":"916ec741e65af072b98e475feaad98c063da1b7c","versionType":"git"},{"version":"07afe1ba288c04280622fa002ed385f1ac0b6fe6","status":"affected","lessThan":"1b466746fe109127fd983100a228cdd1f1f6ece2","versionType":"git"},{"version":"07afe1ba288c04280622fa002ed385f1ac0b6fe6","status":"affected","lessThan":"2b46baa591d0a7c16b62f150917187e70d053be6","versionType":"git"},{"version":"07afe1ba288c04280622fa002ed385f1ac0b6fe6","status":"affected","lessThan":"f12c2de4f542e3220e17e0606f492110064f04cb","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["include/linux/skbuff.h","net/batman-adv/tvlv.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.8","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.8","versionType":"semver"},{"version":"6.12.108","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.49","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.13","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2.3","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["include/linux/skbuff.h","net/batman-adv/tvlv.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/da1f5aa7ec93f2cc17f5cd30efc54f62af433cf2"},{"url":"https://git.kernel.org/stable/c/916ec741e65af072b98e475feaad98c063da1b7c"},{"url":"https://git.kernel.org/stable/c/1b466746fe109127fd983100a228cdd1f1f6ece2"},{"url":"https://git.kernel.org/stable/c/2b46baa591d0a7c16b62f150917187e70d053be6"},{"url":"https://git.kernel.org/stable/c/f12c2de4f542e3220e17e0606f492110064f04cb"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-19T08:44:32.478Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.8","versionEndExcluding":"6.12.108"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.8","versionEndExcluding":"6.18.49"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.8","versionEndExcluding":"7.1.13"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.8","versionEndExcluding":"7.2.3"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.8","versionEndExcluding":"7.3"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}