{"id":"CVE-2026-80847","title":"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 t…","summary":"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 t…","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < eaf4af9bd6975c2eff8d48820937c83032d968dc","Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < cfb44c6028e6f979720315e0772bbd0d4d33ed61","Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 6b8c20bf61924dfc38fefb145c9f7406d73fae53","Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 31cf2349361902769dc323e4dbf4b449795ec288","Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 870a9e42ecc6fe1b8c25d87af043cb0d9c178fe1","Linux 2.6.12"],"published":"2026-09-04","updated":"2026-09-21","sourceUpdated":"2026-09-21T14:17:20.933","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-80847","references":[{"url":"https://git.kernel.org/stable/c/31cf2349361902769dc323e4dbf4b449795ec288","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/6b8c20bf61924dfc38fefb145c9f7406d73fae53","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/870a9e42ecc6fe1b8c25d87af043cb0d9c178fe1","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/cfb44c6028e6f979720315e0772bbd0d4d33ed61","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/eaf4af9bd6975c2eff8d48820937c83032d968dc","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"}],"tags":["nvd","cve.org"],"epss":0.00168,"epssPercentile":0.06501,"ingestedAt":"2026-09-11T16:45:47.925Z","slug":"CVE-2026-80847","body":"## Overview\n\nIn 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.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}