{"id":"CVE-2026-72502","title":"tcp: ipv6: clamp default adverting MSS to avoid GSO_BY_FRAGS (0xFFFF)","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\ntcp: ipv6: clamp default adverting MSS to avoid GSO_BY_FRAGS (0xFFFF)\n\nWhen MTU is large, ip6_default_advmss() can return IPV6_MAXPLEN (65535).\nThis is interpreted by T…","severity":"high","cvss":7.5,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","cvssSource":"cna","vendor":"Linux","product":"Linux","affected":["Linux >= 3953c46c3ac7eef31a9935427371c6f54a22f1ba < 560b33b434e922ef97f9ff23aa2e909ef7aacd5c","Linux >= 3953c46c3ac7eef31a9935427371c6f54a22f1ba < 21f69ac1879bb970588d5e7c12a96e6542f7c1a7","Linux >= 3953c46c3ac7eef31a9935427371c6f54a22f1ba < c0db3dc2ac323b6c4b76adede3b355a9daa6dea8","Linux >= 3953c46c3ac7eef31a9935427371c6f54a22f1ba < 572fff10819dfc359298d1f774839e76a4d96f93","Linux >= 3953c46c3ac7eef31a9935427371c6f54a22f1ba < 8e6214a530c03e341dc1b0a846c8f2b716b3551a","Linux >= 3953c46c3ac7eef31a9935427371c6f54a22f1ba < d774cdbda6634a78d0f2baf201ee5a8c57f3bc0e","Linux >= 3953c46c3ac7eef31a9935427371c6f54a22f1ba < a210791f33345aa87187f7d7a9f3b9b7f4a28e6d","Linux >= 3953c46c3ac7eef31a9935427371c6f54a22f1ba < 2bf43d0e2e6a27d52a7d624e2d6b9116972e8a22","Linux 4.8"],"ssvc":{"exploitation":"none","automatable":"yes","technicalImpact":"partial","timestamp":"2026-10-16T18:51:17.494885Z"},"published":"2026-08-15","updated":"2026-10-16","sourceUpdated":"2026-10-16T18:55:27.761Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-72502","references":[{"url":"https://git.kernel.org/stable/c/560b33b434e922ef97f9ff23aa2e909ef7aacd5c"},{"url":"https://git.kernel.org/stable/c/21f69ac1879bb970588d5e7c12a96e6542f7c1a7"},{"url":"https://git.kernel.org/stable/c/c0db3dc2ac323b6c4b76adede3b355a9daa6dea8"},{"url":"https://git.kernel.org/stable/c/572fff10819dfc359298d1f774839e76a4d96f93"},{"url":"https://git.kernel.org/stable/c/8e6214a530c03e341dc1b0a846c8f2b716b3551a"},{"url":"https://git.kernel.org/stable/c/d774cdbda6634a78d0f2baf201ee5a8c57f3bc0e"},{"url":"https://git.kernel.org/stable/c/a210791f33345aa87187f7d7a9f3b9b7f4a28e6d"},{"url":"https://git.kernel.org/stable/c/2bf43d0e2e6a27d52a7d624e2d6b9116972e8a22"}],"tags":["cve.org"],"epss":0.00716,"epssPercentile":0.52841,"ingestedAt":"2026-10-16T19:46:24.389Z","slug":"CVE-2026-72502","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\ntcp: ipv6: clamp default adverting MSS to avoid GSO_BY_FRAGS (0xFFFF)\n\nWhen MTU is large, ip6_default_advmss() can return IPV6_MAXPLEN (65535).\nThis is interpreted by TCP as mss_clamp, allowing the MSS to reach 65535.\n\nHowever, 0xFFFF is also used as a magic value GSO_BY_FRAGS in the kernel.\nIf a TCP packet with gso_size=0xFFFF is passed to skb_segment(), it will\nbe mistakenly treated as GSO_BY_FRAGS, leading to a NULL pointer\ndereference because local TCP packets do not use frag_list.\n\nFix this by returning min(IPV6_MAXPLEN, GSO_BY_FRAGS - 1) (65534) from\nip6_default_advmss() when MTU is large.\n\nAlso update the stale comment in ip6_default_advmss() which suggested\nthat IPV6_MAXPLEN is returned to mean \"any MSS\".\n\n## Affected\n\n- `Linux >= 3953c46c3ac7eef31a9935427371c6f54a22f1ba < 560b33b434e922ef97f9ff23aa2e909ef7aacd5c`\n- `Linux >= 3953c46c3ac7eef31a9935427371c6f54a22f1ba < 21f69ac1879bb970588d5e7c12a96e6542f7c1a7`\n- `Linux >= 3953c46c3ac7eef31a9935427371c6f54a22f1ba < c0db3dc2ac323b6c4b76adede3b355a9daa6dea8`\n- `Linux >= 3953c46c3ac7eef31a9935427371c6f54a22f1ba < 572fff10819dfc359298d1f774839e76a4d96f93`\n- `Linux >= 3953c46c3ac7eef31a9935427371c6f54a22f1ba < 8e6214a530c03e341dc1b0a846c8f2b716b3551a`\n- `Linux >= 3953c46c3ac7eef31a9935427371c6f54a22f1ba < d774cdbda6634a78d0f2baf201ee5a8c57f3bc0e`\n- `Linux >= 3953c46c3ac7eef31a9935427371c6f54a22f1ba < a210791f33345aa87187f7d7a9f3b9b7f4a28e6d`\n- `Linux >= 3953c46c3ac7eef31a9935427371c6f54a22f1ba < 2bf43d0e2e6a27d52a7d624e2d6b9116972e8a22`\n- `Linux 4.8`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"twilight","depthScore":41,"depthScoreParts":{"impact":41.3,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}