{"id":"CVE-2026-80839","summary":"batman-adv: reject unrepresentable multicast TVLV offsets","details":"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-\u003ehead, 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.","modified":"2026-09-06T03:46:52.885541181Z","published":"2026-09-04T15:54:49.378Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/80xxx/CVE-2026-80839.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/1b466746fe109127fd983100a228cdd1f1f6ece2"},{"type":"WEB","url":"https://git.kernel.org/stable/c/2b46baa591d0a7c16b62f150917187e70d053be6"},{"type":"WEB","url":"https://git.kernel.org/stable/c/916ec741e65af072b98e475feaad98c063da1b7c"},{"type":"WEB","url":"https://git.kernel.org/stable/c/da1f5aa7ec93f2cc17f5cd30efc54f62af433cf2"},{"type":"WEB","url":"https://git.kernel.org/stable/c/f12c2de4f542e3220e17e0606f492110064f04cb"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/80xxx/CVE-2026-80839.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-80839"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"07afe1ba288c04280622fa002ed385f1ac0b6fe6"},{"fixed":"da1f5aa7ec93f2cc17f5cd30efc54f62af433cf2"},{"fixed":"916ec741e65af072b98e475feaad98c063da1b7c"},{"fixed":"1b466746fe109127fd983100a228cdd1f1f6ece2"},{"fixed":"2b46baa591d0a7c16b62f150917187e70d053be6"},{"fixed":"f12c2de4f542e3220e17e0606f492110064f04cb"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-80839.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"6.8.0"},{"fixed":"6.12.108"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.49"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.1.13"}]},{"type":"ECOSYSTEM","events":[{"introduced":"7.2.0"},{"fixed":"7.2.3"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-80839.json"}}],"schema_version":"1.9.0"}