{"api_version":"1","generated_at":"2026-09-11T03:12:49+00:00","cve":"CVE-2026-80793","urls":{"html":"https://cve.report/CVE-2026-80793","api":"https://cve.report/api/cve/CVE-2026-80793.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-80793","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-80793"},"summary":{"title":"ipv4: reject undersized MTUs in ip_do_fragment()","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nipv4: reject undersized MTUs in ip_do_fragment()\n\nip_do_fragment() subtracts the IPv4 header length from the effective\nMTU and passes the resulting payload MTU to ip_frag_next().\n\nIf the effective MTU is smaller than hlen + 8, ip_frag_next() rounds\nthe fragment payload length down to zero. The fragmentation state then\nnever makes forward progress: state->left, state->ptr and state->offset\nstay unchanged while ip_do_fragment() keeps allocating and transmitting\nheader-only fragments until the softlockup detector fires.\n\nThis is reproducible with a route installed using \"mtu lock 20\", but it\nis also reproducible without route MTU lock, for example by forwarding a\npacket to a device whose MTU is 20.\n\nFix it in ip_do_fragment() by rejecting mtu < hlen + 8 with -EMSGSIZE,\nmatching the existing IPv6 fragmentation check.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-09-04 16:18:05","updated_at":"2026-09-04 16:18:05"},"problem_types":[],"metrics":[],"references":[{"url":"https://git.kernel.org/stable/c/74ce7389f8f562d39015f59a00ef7ad6acd37803","name":"https://git.kernel.org/stable/c/74ce7389f8f562d39015f59a00ef7ad6acd37803","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/515b6816ba0c12d8415c88e5f41e6ec029e35cfa","name":"https://git.kernel.org/stable/c/515b6816ba0c12d8415c88e5f41e6ec029e35cfa","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/3556beb8ca86677af2aca5bfbed6f8e790fccc83","name":"https://git.kernel.org/stable/c/3556beb8ca86677af2aca5bfbed6f8e790fccc83","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/c8a74adccaf028223054633b532593101dfcc581","name":"https://git.kernel.org/stable/c/c8a74adccaf028223054633b532593101dfcc581","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/a716a64a4ba68cd46f2745fba2b1099fe8e0aa59","name":"https://git.kernel.org/stable/c/a716a64a4ba68cd46f2745fba2b1099fe8e0aa59","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/b0ea911453ce7210e8200a07a94d2458bd1e6430","name":"https://git.kernel.org/stable/c/b0ea911453ce7210e8200a07a94d2458bd1e6430","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/d9d1a676b033acabf8e5645f730486d1f8204a3f","name":"https://git.kernel.org/stable/c/d9d1a676b033acabf8e5645f730486d1f8204a3f","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/36e0741833bd823866f8cb9f112f37cea1a70b60","name":"https://git.kernel.org/stable/c/36e0741833bd823866f8cb9f112f37cea1a70b60","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/c0726f0caf8c6b3208552949e17d23634a2f3129","name":"https://git.kernel.org/stable/c/c0726f0caf8c6b3208552949e17d23634a2f3129","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-80793","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-80793","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 a716a64a4ba68cd46f2745fba2b1099fe8e0aa59 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 515b6816ba0c12d8415c88e5f41e6ec029e35cfa git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 74ce7389f8f562d39015f59a00ef7ad6acd37803 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 b0ea911453ce7210e8200a07a94d2458bd1e6430 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 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original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":{"cve_year":"2026","cve_id":"80793","cve":"CVE-2026-80793","epss":"0.001950000","percentile":"0.092870000","score_date":"2026-09-07","updated_at":"2026-09-08 00:05:27"},"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["net/ipv4/ip_output.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"a716a64a4ba68cd46f2745fba2b1099fe8e0aa59","status":"affected","version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","versionType":"git"},{"lessThan":"515b6816ba0c12d8415c88e5f41e6ec029e35cfa","status":"affected","version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","versionType":"git"},{"lessThan":"74ce7389f8f562d39015f59a00ef7ad6acd37803","status":"affected","version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","versionType":"git"},{"lessThan":"b0ea911453ce7210e8200a07a94d2458bd1e6430","status":"affected","version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","versionType":"git"},{"lessThan":"36e0741833bd823866f8cb9f112f37cea1a70b60","status":"affected","version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","versionType":"git"},{"lessThan":"d9d1a676b033acabf8e5645f730486d1f8204a3f","status":"affected","version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","versionType":"git"},{"lessThan":"3556beb8ca86677af2aca5bfbed6f8e790fccc83","status":"affected","version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","versionType":"git"},{"lessThan":"c8a74adccaf028223054633b532593101dfcc581","status":"affected","version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","versionType":"git"},{"lessThan":"c0726f0caf8c6b3208552949e17d23634a2f3129","status":"affected","version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["net/ipv4/ip_output.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"2.6.12"},{"lessThan":"2.6.12","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"5.10.*","status":"unaffected","version":"5.10.267","versionType":"semver"},{"lessThanOrEqual":"5.15.*","status":"unaffected","version":"5.15.218","versionType":"semver"},{"lessThanOrEqual":"6.1.*","status":"unaffected","version":"6.1.185","versionType":"semver"},{"lessThanOrEqual":"6.6.*","status":"unaffected","version":"6.6.154","versionType":"semver"},{"lessThanOrEqual":"6.12.*","status":"unaffected","version":"6.12.106","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.47","versionType":"semver"},{"lessThanOrEqual":"7.1.*","status":"unaffected","version":"7.1.11","versionType":"semver"},{"lessThanOrEqual":"7.2.*","status":"unaffected","version":"7.2.1","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.3-rc1","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"5.10.267","versionStartIncluding":"2.6.12","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"5.15.218","versionStartIncluding":"2.6.12","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.1.185","versionStartIncluding":"2.6.12","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.6.154","versionStartIncluding":"2.6.12","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.12.106","versionStartIncluding":"2.6.12","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.47","versionStartIncluding":"2.6.12","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.1.11","versionStartIncluding":"2.6.12","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2.1","versionStartIncluding":"2.6.12","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.3-rc1","versionStartIncluding":"2.6.12","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nipv4: reject undersized MTUs in ip_do_fragment()\n\nip_do_fragment() subtracts the IPv4 header length from the effective\nMTU and passes the resulting payload MTU to ip_frag_next().\n\nIf the effective MTU is smaller than hlen + 8, ip_frag_next() rounds\nthe fragment payload length down to zero. The fragmentation state then\nnever makes forward progress: state->left, state->ptr and state->offset\nstay unchanged while ip_do_fragment() keeps allocating and transmitting\nheader-only fragments until the softlockup detector fires.\n\nThis is reproducible with a route installed using \"mtu lock 20\", but it\nis also reproducible without route MTU lock, for example by forwarding a\npacket to a device whose MTU is 20.\n\nFix it in ip_do_fragment() by rejecting mtu < hlen + 8 with -EMSGSIZE,\nmatching the existing IPv6 fragmentation check."}],"providerMetadata":{"dateUpdated":"2026-09-04T15:13:05.814Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/a716a64a4ba68cd46f2745fba2b1099fe8e0aa59"},{"url":"https://git.kernel.org/stable/c/515b6816ba0c12d8415c88e5f41e6ec029e35cfa"},{"url":"https://git.kernel.org/stable/c/74ce7389f8f562d39015f59a00ef7ad6acd37803"},{"url":"https://git.kernel.org/stable/c/b0ea911453ce7210e8200a07a94d2458bd1e6430"},{"url":"https://git.kernel.org/stable/c/36e0741833bd823866f8cb9f112f37cea1a70b60"},{"url":"https://git.kernel.org/stable/c/d9d1a676b033acabf8e5645f730486d1f8204a3f"},{"url":"https://git.kernel.org/stable/c/3556beb8ca86677af2aca5bfbed6f8e790fccc83"},{"url":"https://git.kernel.org/stable/c/c8a74adccaf028223054633b532593101dfcc581"},{"url":"https://git.kernel.org/stable/c/c0726f0caf8c6b3208552949e17d23634a2f3129"}],"title":"ipv4: reject undersized MTUs in ip_do_fragment()","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-80793","datePublished":"2026-09-04T15:13:05.814Z","dateReserved":"2026-08-26T14:34:25.793Z","dateUpdated":"2026-09-04T15:13:05.814Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-09-04 16:18:05","lastModifiedDate":"2026-09-04 16:18:05","problem_types":[],"metrics":[],"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"80793","Ordinal":"1","Title":"ipv4: reject undersized MTUs in ip_do_fragment()","CVE":"CVE-2026-80793","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"80793","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nipv4: reject undersized MTUs in ip_do_fragment()\n\nip_do_fragment() subtracts the IPv4 header length from the effective\nMTU and passes the resulting payload MTU to ip_frag_next().\n\nIf the effective MTU is smaller than hlen + 8, ip_frag_next() rounds\nthe fragment payload length down to zero. The fragmentation state then\nnever makes forward progress: state->left, state->ptr and state->offset\nstay unchanged while ip_do_fragment() keeps allocating and transmitting\nheader-only fragments until the softlockup detector fires.\n\nThis is reproducible with a route installed using \"mtu lock 20\", but it\nis also reproducible without route MTU lock, for example by forwarding a\npacket to a device whose MTU is 20.\n\nFix it in ip_do_fragment() by rejecting mtu < hlen + 8 with -EMSGSIZE,\nmatching the existing IPv6 fragmentation check.","Type":"Description","Title":"ipv4: reject undersized MTUs in ip_do_fragment()"}]}}}