{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-98852","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2026-09-25T10:25:14.376Z","datePublished":"2026-10-18T15:50:55.946Z","dateUpdated":"2026-10-21T12:57:32.027Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-10-21T12:57:32.027Z"},"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet: extend IPv6 exthdr detection of tunneled packets\n\nCommit c4336a07eb6b (\"net: correctly handle tunneled traffic on IPV6_CSUM\nGSO fallback\") split skb_gso_has_extension_hdr() into mutually exclusive\nbranches on skb->encapsulation. This did not yet address all paths:\n\n1. With skb->encapsulation set, the outer header is not checked. IPv6\n   tunnels such as ip6_gre and ip6_tunnel add an outer Destination\n   Options header by default (encap_limit). Their GSO packets skip\n   software GSO, then skb_csum_hwoffload_help() sees the outer extension\n   header and calls skb_checksum_help() on the GSO skb, which warns and\n   drops it.\n\n2. Tunnels over IPv6 without an outer transport header, such as\n   ip6_tunnel, leave skb->transport_header at the inner transport\n   header. skb_network_header_len() then spans the outer IPv6, tunnel\n   and inner IP headers, a false positive.\n\n3. UDP tunnels without an inner network header, such as SCTP-in-UDP or\n   PSP, have no inner IPv6 header to check. Decide on the outer header\n   alone.\n\n4. Directly dereferencing inner_ip_hdr(skb)->version without\n   skb_header_pointer() is unsafe.\n\nInstead, check ipv6_ext_hdr(nexthdr) on the outer IPv6 header and, if\nset, on the inner IPv6 header. Read the headers with skb_header_pointer().\nKeep the skb_network_header_len() check when !skb->encapsulation to also\ncatch encapsulated packets without skb->encapsulation (e.g., virtio).\n\nUse the same helper in skb_csum_hwoffload_help(). Its open coded test\nhas the false positive of (2) and ignores the inner header.\n\nBackground: checksum offload of tunneled packets invariants:\n\nNon-GSO skb:\n- If the inner packet is CHECKSUM_PARTIAL, Local Checksum Offload computes\n  the outer checksum in software and the device offloads only the inner L4\n  checksum.\n- If the inner packet is CHECKSUM_NONE (e.g., SCTP-in-UDP, ESP-in-UDP,\n  Remote Checksum Offload), the device offloads the outer UDP or GRE\n  checksum instead.\n\nGSO skb:\n- A device with NETIF_F_GSO_UDP_TUNNEL_CSUM or NETIF_F_GSO_GRE_CSUM\n  computes both inner and outer checksums per segment.\n  The outer checksum is seeded with only the pseudo-header checksum.\n\nA NETIF_F_IPV6_CSUM device must parse through the outer headers to\nreach the inner ones."}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/core/dev.c"],"versions":[{"version":"ed71cf465c75f5688b07a35d373cd1d6b589c8ea","lessThan":"fdbd83c2d929ec968b37d2f75149a79440e328ff","status":"affected","versionType":"git"},{"version":"33670f780e0120c3dacda188c512bbffe0b6044c","lessThan":"44ba9dc568c878b699d05e7cf699572dc9df4b59","status":"affected","versionType":"git"},{"version":"a98b78116a27e2a57b696b569b2cb431c95cf9b6","lessThan":"aa480f05aed7a9eee87d4a6fc90647fe9679c670","status":"affected","versionType":"git"},{"version":"c4336a07eb6b2526dc2b62928b5104b41a7f81f5","lessThan":"cabacdf98e09eb74599c4d97d7bd7fd659598fb7","status":"affected","versionType":"git"},{"version":"c4336a07eb6b2526dc2b62928b5104b41a7f81f5","lessThan":"5f0764cb1c81a9712bce605d38efe6d844a70b29","status":"affected","versionType":"git"},{"version":"2094a7cf91b71367b649f991aacc7b579f793d0b","status":"affected","versionType":"git"},{"version":"732fdeb2987c94b439d51f5cb9addddc2fc48c42","status":"affected","versionType":"git"},{"version":"6.6.134","lessThan":"6.6.160","status":"affected","versionType":"semver"},{"version":"6.12.81","lessThan":"6.12.113","status":"affected","versionType":"semver"},{"version":"6.18.22","lessThan":"6.18.56","status":"affected","versionType":"semver"},{"version":"6.1.168","lessThan":"6.2","status":"affected","versionType":"semver"},{"version":"6.19.12","lessThan":"6.20","status":"affected","versionType":"semver"}]},{"product":"Linux","vendor":"Linux","defaultStatus":"affected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/core/dev.c"],"versions":[{"version":"7.0","status":"affected"},{"version":"0","lessThan":"7.0","status":"unaffected","versionType":"semver"},{"version":"6.6.160","lessThanOrEqual":"6.6.*","status":"unaffected","versionType":"semver"},{"version":"6.12.113","lessThanOrEqual":"6.12.*","status":"unaffected","versionType":"semver"},{"version":"6.18.56","lessThanOrEqual":"6.18.*","status":"unaffected","versionType":"semver"},{"version":"7.2.10","lessThanOrEqual":"7.2.*","status":"unaffected","versionType":"semver"},{"version":"7.3","lessThanOrEqual":"*","status":"unaffected","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.6.134","versionEndExcluding":"6.6.160"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.12.81","versionEndExcluding":"6.12.113"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.18.22","versionEndExcluding":"6.18.56"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"7.0","versionEndExcluding":"7.2.10"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"7.0","versionEndExcluding":"7.3"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.1.168"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.19.12"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/fdbd83c2d929ec968b37d2f75149a79440e328ff"},{"url":"https://git.kernel.org/stable/c/44ba9dc568c878b699d05e7cf699572dc9df4b59"},{"url":"https://git.kernel.org/stable/c/aa480f05aed7a9eee87d4a6fc90647fe9679c670"},{"url":"https://git.kernel.org/stable/c/cabacdf98e09eb74599c4d97d7bd7fd659598fb7"},{"url":"https://git.kernel.org/stable/c/5f0764cb1c81a9712bce605d38efe6d844a70b29"}],"title":"net: extend IPv6 exthdr detection of tunneled packets","x_generator":{"engine":"bippy-1.2.0"}}}}