{"api_version":"1","generated_at":"2026-10-01T11:10:44+00:00","cve":"CVE-2026-97984","urls":{"html":"https://cve.report/CVE-2026-97984","api":"https://cve.report/api/cve/CVE-2026-97984.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-97984","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-97984"},"summary":{"title":"net: ipv6: Fix UDP length overflow with PMTU discover and big MTU","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet: ipv6: Fix UDP length overflow with PMTU discover and big MTU\n\nThis commit bounds cork->base.fragsize to IP6_MAX_MTU for UDP sockets to\navoid a possible overflow of UDP length that triggers a WARN in\nudp_set_len_short when setsockopt IPV6_MTU_DISCOVER is set to\nIPV6_PMTUDISC_DO or IPV6_PMTUDISC_PROBE, and a large packet is sent over\na netdev with an unusually large MTU.\n\nSteps to reproduce (included in the new selftest):\n\n1. Set device MTU bigger than IP6_MAX_MTU. cork->base.fragsize will be\n   set to that MTU in ip6_setup_cork.\n2. Set IPV6_MTU_DISCOVER to IPV6_PMTUDISC_PROBE or IPV6_PMTUDISC_DO. It\n   lets maxnonfragsize be set to device MTU (cork->fragsize) in\n   __ip6_append_data, rather than to IP6_MAX_MTU.\n3. Send 65528 bytes of payload (+8 bytes of UDP header, +40 bytes of\n   IPv6 header). Device MTU allows it (it's only one byte bigger than\n   IP6_MAX_MTU, and the device MTU is bigger than that).\n4. The UDP length in the built packet is 65536, which overflows the\n   16-bit length field and triggers the WARN in udp_set_len_short.\n\nTo avoid breaking sending UDP jumbograms over raw IPv6 sockets, limit\nthe change to UDP sockets only.\n\nThe original overflow bug with IPv6 and IPV6_PMTUDISC_DO seems to\npredate git history (verified reproduction on 2.6.21), was fixed later,\nand then reappeared in commit 427faee167bc (\"net: ipv6: introduce\nip6_dst_mtu_maybe_forward\"), which is chosen as the Fixes tag here. The\noverflow with IPV6_PMTUDISC_PROBE reproduces since its introduction in\ncommit 628a5c561890 (\"[INET]: Add IP(V6)_PMTUDISC_RPOBE\").","state":"PUBLISHED","assigner":"Linux","published_at":"2026-09-25 11:17:26","updated_at":"2026-09-25 11:17:26"},"problem_types":[],"metrics":[],"references":[{"url":"https://git.kernel.org/stable/c/ce66352d3eb21825410af8b91db7cc4bb8e22c98","name":"https://git.kernel.org/stable/c/ce66352d3eb21825410af8b91db7cc4bb8e22c98","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/e01b7c176d9af2b7c22bb3fe12cf9a7904f99fdc","name":"https://git.kernel.org/stable/c/e01b7c176d9af2b7c22bb3fe12cf9a7904f99fdc","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/1d56a00ec91f2885c64ea5b8cea18cb746b91bbb","name":"https://git.kernel.org/stable/c/1d56a00ec91f2885c64ea5b8cea18cb746b91bbb","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/0ae10b6be49b425827659b23bcce498f80eb7182","name":"https://git.kernel.org/stable/c/0ae10b6be49b425827659b23bcce498f80eb7182","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-97984","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-97984","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 427faee167bce4ccb0b22f6815a9ac509e31d4c3 1d56a00ec91f2885c64ea5b8cea18cb746b91bbb git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 427faee167bce4ccb0b22f6815a9ac509e31d4c3 ce66352d3eb21825410af8b91db7cc4bb8e22c98 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 427faee167bce4ccb0b22f6815a9ac509e31d4c3 e01b7c176d9af2b7c22bb3fe12cf9a7904f99fdc git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 427faee167bce4ccb0b22f6815a9ac509e31d4c3 0ae10b6be49b425827659b23bcce498f80eb7182 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 5.15","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 5.15 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.12.111 6.12.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.53 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2.7 7.2.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.3-rc3 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":{"cve_year":"2026","cve_id":"97984","cve":"CVE-2026-97984","epss":"0.001680000","percentile":"0.053850000","score_date":"2026-09-27","updated_at":"2026-09-28 00:02:24"},"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["net/ipv6/ip6_output.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"1d56a00ec91f2885c64ea5b8cea18cb746b91bbb","status":"affected","version":"427faee167bce4ccb0b22f6815a9ac509e31d4c3","versionType":"git"},{"lessThan":"ce66352d3eb21825410af8b91db7cc4bb8e22c98","status":"affected","version":"427faee167bce4ccb0b22f6815a9ac509e31d4c3","versionType":"git"},{"lessThan":"e01b7c176d9af2b7c22bb3fe12cf9a7904f99fdc","status":"affected","version":"427faee167bce4ccb0b22f6815a9ac509e31d4c3","versionType":"git"},{"lessThan":"0ae10b6be49b425827659b23bcce498f80eb7182","status":"affected","version":"427faee167bce4ccb0b22f6815a9ac509e31d4c3","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["net/ipv6/ip6_output.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"5.15"},{"lessThan":"5.15","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"6.12.*","status":"unaffected","version":"6.12.111","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.53","versionType":"semver"},{"lessThanOrEqual":"7.2.*","status":"unaffected","version":"7.2.7","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.3-rc3","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.12.111","versionStartIncluding":"5.15","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.53","versionStartIncluding":"5.15","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2.7","versionStartIncluding":"5.15","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.3-rc3","versionStartIncluding":"5.15","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet: ipv6: Fix UDP length overflow with PMTU discover and big MTU\n\nThis commit bounds cork->base.fragsize to IP6_MAX_MTU for UDP sockets to\navoid a possible overflow of UDP length that triggers a WARN in\nudp_set_len_short when setsockopt IPV6_MTU_DISCOVER is set to\nIPV6_PMTUDISC_DO or IPV6_PMTUDISC_PROBE, and a large packet is sent over\na netdev with an unusually large MTU.\n\nSteps to reproduce (included in the new selftest):\n\n1. Set device MTU bigger than IP6_MAX_MTU. cork->base.fragsize will be\n   set to that MTU in ip6_setup_cork.\n2. Set IPV6_MTU_DISCOVER to IPV6_PMTUDISC_PROBE or IPV6_PMTUDISC_DO. It\n   lets maxnonfragsize be set to device MTU (cork->fragsize) in\n   __ip6_append_data, rather than to IP6_MAX_MTU.\n3. Send 65528 bytes of payload (+8 bytes of UDP header, +40 bytes of\n   IPv6 header). Device MTU allows it (it's only one byte bigger than\n   IP6_MAX_MTU, and the device MTU is bigger than that).\n4. The UDP length in the built packet is 65536, which overflows the\n   16-bit length field and triggers the WARN in udp_set_len_short.\n\nTo avoid breaking sending UDP jumbograms over raw IPv6 sockets, limit\nthe change to UDP sockets only.\n\nThe original overflow bug with IPv6 and IPV6_PMTUDISC_DO seems to\npredate git history (verified reproduction on 2.6.21), was fixed later,\nand then reappeared in commit 427faee167bc (\"net: ipv6: introduce\nip6_dst_mtu_maybe_forward\"), which is chosen as the Fixes tag here. The\noverflow with IPV6_PMTUDISC_PROBE reproduces since its introduction in\ncommit 628a5c561890 (\"[INET]: Add IP(V6)_PMTUDISC_RPOBE\")."}],"providerMetadata":{"dateUpdated":"2026-09-25T10:23:19.568Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/1d56a00ec91f2885c64ea5b8cea18cb746b91bbb"},{"url":"https://git.kernel.org/stable/c/ce66352d3eb21825410af8b91db7cc4bb8e22c98"},{"url":"https://git.kernel.org/stable/c/e01b7c176d9af2b7c22bb3fe12cf9a7904f99fdc"},{"url":"https://git.kernel.org/stable/c/0ae10b6be49b425827659b23bcce498f80eb7182"}],"title":"net: ipv6: Fix UDP length overflow with PMTU discover and big MTU","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-97984","datePublished":"2026-09-25T10:23:19.568Z","dateReserved":"2026-09-25T10:18:58.208Z","dateUpdated":"2026-09-25T10:23:19.568Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-09-25 11:17:26","lastModifiedDate":"2026-09-25 11:17:26","problem_types":[],"metrics":[],"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"97984","Ordinal":"1","Title":"net: ipv6: Fix UDP length overflow with PMTU discover and big MT","CVE":"CVE-2026-97984","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"97984","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet: ipv6: Fix UDP length overflow with PMTU discover and big MTU\n\nThis commit bounds cork->base.fragsize to IP6_MAX_MTU for UDP sockets to\navoid a possible overflow of UDP length that triggers a WARN in\nudp_set_len_short when setsockopt IPV6_MTU_DISCOVER is set to\nIPV6_PMTUDISC_DO or IPV6_PMTUDISC_PROBE, and a large packet is sent over\na netdev with an unusually large MTU.\n\nSteps to reproduce (included in the new selftest):\n\n1. Set device MTU bigger than IP6_MAX_MTU. cork->base.fragsize will be\n   set to that MTU in ip6_setup_cork.\n2. Set IPV6_MTU_DISCOVER to IPV6_PMTUDISC_PROBE or IPV6_PMTUDISC_DO. It\n   lets maxnonfragsize be set to device MTU (cork->fragsize) in\n   __ip6_append_data, rather than to IP6_MAX_MTU.\n3. Send 65528 bytes of payload (+8 bytes of UDP header, +40 bytes of\n   IPv6 header). Device MTU allows it (it's only one byte bigger than\n   IP6_MAX_MTU, and the device MTU is bigger than that).\n4. The UDP length in the built packet is 65536, which overflows the\n   16-bit length field and triggers the WARN in udp_set_len_short.\n\nTo avoid breaking sending UDP jumbograms over raw IPv6 sockets, limit\nthe change to UDP sockets only.\n\nThe original overflow bug with IPv6 and IPV6_PMTUDISC_DO seems to\npredate git history (verified reproduction on 2.6.21), was fixed later,\nand then reappeared in commit 427faee167bc (\"net: ipv6: introduce\nip6_dst_mtu_maybe_forward\"), which is chosen as the Fixes tag here. The\noverflow with IPV6_PMTUDISC_PROBE reproduces since its introduction in\ncommit 628a5c561890 (\"[INET]: Add IP(V6)_PMTUDISC_RPOBE\").","Type":"Description","Title":"net: ipv6: Fix UDP length overflow with PMTU discover and big MT"}]}}}