{"api_version":"1","generated_at":"2026-10-24T12:30:32+00:00","cve":"CVE-2026-98852","urls":{"html":"https://cve.report/CVE-2026-98852","api":"https://cve.report/api/cve/CVE-2026-98852.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-98852","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-98852"},"summary":{"title":"net: extend IPv6 exthdr detection of tunneled packets","description":"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.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-10-18 16:17:39","updated_at":"2026-10-21 13:21:49"},"problem_types":[],"metrics":[],"references":[{"url":"https://git.kernel.org/stable/c/5f0764cb1c81a9712bce605d38efe6d844a70b29","name":"https://git.kernel.org/stable/c/5f0764cb1c81a9712bce605d38efe6d844a70b29","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/fdbd83c2d929ec968b37d2f75149a79440e328ff","name":"https://git.kernel.org/stable/c/fdbd83c2d929ec968b37d2f75149a79440e328ff","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/44ba9dc568c878b699d05e7cf699572dc9df4b59","name":"https://git.kernel.org/stable/c/44ba9dc568c878b699d05e7cf699572dc9df4b59","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/aa480f05aed7a9eee87d4a6fc90647fe9679c670","name":"https://git.kernel.org/stable/c/aa480f05aed7a9eee87d4a6fc90647fe9679c670","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/cabacdf98e09eb74599c4d97d7bd7fd659598fb7","name":"https://git.kernel.org/stable/c/cabacdf98e09eb74599c4d97d7bd7fd659598fb7","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-98852","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-98852","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected ed71cf465c75f5688b07a35d373cd1d6b589c8ea fdbd83c2d929ec968b37d2f75149a79440e328ff git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 33670f780e0120c3dacda188c512bbffe0b6044c 44ba9dc568c878b699d05e7cf699572dc9df4b59 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected a98b78116a27e2a57b696b569b2cb431c95cf9b6 aa480f05aed7a9eee87d4a6fc90647fe9679c670 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected c4336a07eb6b2526dc2b62928b5104b41a7f81f5 cabacdf98e09eb74599c4d97d7bd7fd659598fb7 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected c4336a07eb6b2526dc2b62928b5104b41a7f81f5 5f0764cb1c81a9712bce605d38efe6d844a70b29 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 2094a7cf91b71367b649f991aacc7b579f793d0b git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 732fdeb2987c94b439d51f5cb9addddc2fc48c42 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.6.134 6.6.160 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.12.81 6.12.113 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.18.22 6.18.56 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.1.168 6.2 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.19.12 6.20 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 7.0","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.0 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.6.160 6.6.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.12.113 6.12.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.56 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2.10 7.2.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.3 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":{"cve_year":"2026","cve_id":"98852","cve":"CVE-2026-98852","epss":"0.001570000","percentile":"0.044430000","score_date":"2026-10-21","updated_at":"2026-10-22 00:15:10"},"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["net/core/dev.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"fdbd83c2d929ec968b37d2f75149a79440e328ff","status":"affected","version":"ed71cf465c75f5688b07a35d373cd1d6b589c8ea","versionType":"git"},{"lessThan":"44ba9dc568c878b699d05e7cf699572dc9df4b59","status":"affected","version":"33670f780e0120c3dacda188c512bbffe0b6044c","versionType":"git"},{"lessThan":"aa480f05aed7a9eee87d4a6fc90647fe9679c670","status":"affected","version":"a98b78116a27e2a57b696b569b2cb431c95cf9b6","versionType":"git"},{"lessThan":"cabacdf98e09eb74599c4d97d7bd7fd659598fb7","status":"affected","version":"c4336a07eb6b2526dc2b62928b5104b41a7f81f5","versionType":"git"},{"lessThan":"5f0764cb1c81a9712bce605d38efe6d844a70b29","status":"affected","version":"c4336a07eb6b2526dc2b62928b5104b41a7f81f5","versionType":"git"},{"status":"affected","version":"2094a7cf91b71367b649f991aacc7b579f793d0b","versionType":"git"},{"status":"affected","version":"732fdeb2987c94b439d51f5cb9addddc2fc48c42","versionType":"git"},{"lessThan":"6.6.160","status":"affected","version":"6.6.134","versionType":"semver"},{"lessThan":"6.12.113","status":"affected","version":"6.12.81","versionType":"semver"},{"lessThan":"6.18.56","status":"affected","version":"6.18.22","versionType":"semver"},{"lessThan":"6.2","status":"affected","version":"6.1.168","versionType":"semver"},{"lessThan":"6.20","status":"affected","version":"6.19.12","versionType":"semver"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["net/core/dev.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"7.0"},{"lessThan":"7.0","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"6.6.*","status":"unaffected","version":"6.6.160","versionType":"semver"},{"lessThanOrEqual":"6.12.*","status":"unaffected","version":"6.12.113","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.56","versionType":"semver"},{"lessThanOrEqual":"7.2.*","status":"unaffected","version":"7.2.10","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.3","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.6.160","versionStartIncluding":"6.6.134","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.12.113","versionStartIncluding":"6.12.81","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.56","versionStartIncluding":"6.18.22","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2.10","versionStartIncluding":"7.0","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.3","versionStartIncluding":"7.0","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","vulnerable":true}],"negate":false,"operator":"OR"}]}],"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."}],"providerMetadata":{"dateUpdated":"2026-10-21T12:57:32.027Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"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"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-98852","datePublished":"2026-10-18T15:50:55.946Z","dateReserved":"2026-09-25T10:25:14.376Z","dateUpdated":"2026-10-21T12:57:32.027Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-10-18 16:17:39","lastModifiedDate":"2026-10-21 13:21:49","problem_types":[],"metrics":[],"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"98852","Ordinal":"1","Title":"net: extend IPv6 exthdr detection of tunneled packets","CVE":"CVE-2026-98852","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"98852","Ordinal":"1","NoteData":"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.","Type":"Description","Title":"net: extend IPv6 exthdr detection of tunneled packets"}]}}}