{"api_version":"1","generated_at":"2026-09-16T09:31:19+00:00","cve":"CVE-2026-80847","urls":{"html":"https://cve.report/CVE-2026-80847","api":"https://cve.report/api/cve/CVE-2026-80847.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-80847","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-80847"},"summary":{"title":"tcp: clamp route advmss to TCP_MIN_MSS","description":"In the Linux kernel, the following vulnerability has been resolved:\n\ntcp: clamp route advmss to TCP_MIN_MSS\n\ntcp_select_initial_window() assumes that callers never pass an MSS\nsmaller than 1, but route-derived advmss values can violate that\nassumption.\n\nA too-small explicit RTAX_ADVMSS is one way to get there, but it is not\nthe only one. The same divide-by-zero can also be reached through the\n\"default advmss\" path when RTAX_ADVMSS is left at 0 and the effective\nadvmss is later driven down by route MTU and min_adv_mss.\n\nIntroduce a tcp_dst_advmss() helper that clamps route advmss to\nTCP_MIN_MSS before TCP consumes it, and use it in the TCP paths that\nderive advmss from dst metrics. This keeps the effective MSS from\ndropping to zero before tcp_select_initial_window() rounds the receive\nwindow.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-09-04 16:18:13","updated_at":"2026-09-11 10:16:51"},"problem_types":[],"metrics":[],"references":[{"url":"https://git.kernel.org/stable/c/31cf2349361902769dc323e4dbf4b449795ec288","name":"https://git.kernel.org/stable/c/31cf2349361902769dc323e4dbf4b449795ec288","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/6b8c20bf61924dfc38fefb145c9f7406d73fae53","name":"https://git.kernel.org/stable/c/6b8c20bf61924dfc38fefb145c9f7406d73fae53","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/870a9e42ecc6fe1b8c25d87af043cb0d9c178fe1","name":"https://git.kernel.org/stable/c/870a9e42ecc6fe1b8c25d87af043cb0d9c178fe1","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/cfb44c6028e6f979720315e0772bbd0d4d33ed61","name":"https://git.kernel.org/stable/c/cfb44c6028e6f979720315e0772bbd0d4d33ed61","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-80847","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-80847","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 cfb44c6028e6f979720315e0772bbd0d4d33ed61 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 6b8c20bf61924dfc38fefb145c9f7406d73fae53 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 31cf2349361902769dc323e4dbf4b449795ec288 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 870a9e42ecc6fe1b8c25d87af043cb0d9c178fe1 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 2.6.12","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 2.6.12 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.51 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.1.13 7.1.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2.3 7.2.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.3-rc1 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":{"cve_year":"2026","cve_id":"80847","cve":"CVE-2026-80847","epss":"0.001680000","percentile":"0.063710000","score_date":"2026-09-13","updated_at":"2026-09-14 00:18:04"},"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["include/net/tcp.h","net/ipv4/tcp_ipv4.c","net/ipv4/tcp_minisocks.c","net/ipv4/tcp_output.c","net/ipv6/tcp_ipv6.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"cfb44c6028e6f979720315e0772bbd0d4d33ed61","status":"affected","version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","versionType":"git"},{"lessThan":"6b8c20bf61924dfc38fefb145c9f7406d73fae53","status":"affected","version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","versionType":"git"},{"lessThan":"31cf2349361902769dc323e4dbf4b449795ec288","status":"affected","version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","versionType":"git"},{"lessThan":"870a9e42ecc6fe1b8c25d87af043cb0d9c178fe1","status":"affected","version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["include/net/tcp.h","net/ipv4/tcp_ipv4.c","net/ipv4/tcp_minisocks.c","net/ipv4/tcp_output.c","net/ipv6/tcp_ipv6.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":"6.18.*","status":"unaffected","version":"6.18.51","versionType":"semver"},{"lessThanOrEqual":"7.1.*","status":"unaffected","version":"7.1.13","versionType":"semver"},{"lessThanOrEqual":"7.2.*","status":"unaffected","version":"7.2.3","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":"6.18.51","versionStartIncluding":"2.6.12","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.1.13","versionStartIncluding":"2.6.12","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2.3","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\ntcp: clamp route advmss to TCP_MIN_MSS\n\ntcp_select_initial_window() assumes that callers never pass an MSS\nsmaller than 1, but route-derived advmss values can violate that\nassumption.\n\nA too-small explicit RTAX_ADVMSS is one way to get there, but it is not\nthe only one. The same divide-by-zero can also be reached through the\n\"default advmss\" path when RTAX_ADVMSS is left at 0 and the effective\nadvmss is later driven down by route MTU and min_adv_mss.\n\nIntroduce a tcp_dst_advmss() helper that clamps route advmss to\nTCP_MIN_MSS before TCP consumes it, and use it in the TCP paths that\nderive advmss from dst metrics. This keeps the effective MSS from\ndropping to zero before tcp_select_initial_window() rounds the receive\nwindow."}],"providerMetadata":{"dateUpdated":"2026-09-11T09:57:09.499Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/cfb44c6028e6f979720315e0772bbd0d4d33ed61"},{"url":"https://git.kernel.org/stable/c/6b8c20bf61924dfc38fefb145c9f7406d73fae53"},{"url":"https://git.kernel.org/stable/c/31cf2349361902769dc323e4dbf4b449795ec288"},{"url":"https://git.kernel.org/stable/c/870a9e42ecc6fe1b8c25d87af043cb0d9c178fe1"}],"title":"tcp: clamp route advmss to TCP_MIN_MSS","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-80847","datePublished":"2026-09-04T15:54:57.441Z","dateReserved":"2026-08-26T14:34:25.797Z","dateUpdated":"2026-09-11T09:57:09.499Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-09-04 16:18:13","lastModifiedDate":"2026-09-11 10:16:51","problem_types":[],"metrics":[],"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"80847","Ordinal":"1","Title":"tcp: clamp route advmss to TCP_MIN_MSS","CVE":"CVE-2026-80847","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"80847","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\ntcp: clamp route advmss to TCP_MIN_MSS\n\ntcp_select_initial_window() assumes that callers never pass an MSS\nsmaller than 1, but route-derived advmss values can violate that\nassumption.\n\nA too-small explicit RTAX_ADVMSS is one way to get there, but it is not\nthe only one. The same divide-by-zero can also be reached through the\n\"default advmss\" path when RTAX_ADVMSS is left at 0 and the effective\nadvmss is later driven down by route MTU and min_adv_mss.\n\nIntroduce a tcp_dst_advmss() helper that clamps route advmss to\nTCP_MIN_MSS before TCP consumes it, and use it in the TCP paths that\nderive advmss from dst metrics. This keeps the effective MSS from\ndropping to zero before tcp_select_initial_window() rounds the receive\nwindow.","Type":"Description","Title":"tcp: clamp route advmss to TCP_MIN_MSS"}]}}}