{"id":"CVE-2026-43036","title":"net: use skb_header_pointer() for TCPv4 GSO frag_off check","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet: use skb_header_pointer() for TCPv4 GSO frag_off check\n\nSyzbot reported a KMSAN uninit-value warning in gso_features_check()\ncalled from netif_skb_features() [1].\n\n…","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= cbc53e08a793b073e79f42ca33f1f3568703540d < 5057502630fbc8ce468ff617ff59af275960b537","Linux >= cbc53e08a793b073e79f42ca33f1f3568703540d < f7a6cd508e9e825a2c69fa9e13d41ee156852f25","Linux >= cbc53e08a793b073e79f42ca33f1f3568703540d < cc91202fc20a44aab4c206f12a2bfe05da936051","Linux >= cbc53e08a793b073e79f42ca33f1f3568703540d < d970341cfa5594614c7a6634886c7688b4f5cafd","Linux >= cbc53e08a793b073e79f42ca33f1f3568703540d < ddc748a391dd8642ba6b2e4fe22e7f2ddf84b7f0","Linux 4.7"],"published":"2026-05-01","updated":"2026-10-21","sourceUpdated":"2026-10-21T12:39:54.503Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-43036","references":[{"url":"https://git.kernel.org/stable/c/5057502630fbc8ce468ff617ff59af275960b537"},{"url":"https://git.kernel.org/stable/c/f7a6cd508e9e825a2c69fa9e13d41ee156852f25"},{"url":"https://git.kernel.org/stable/c/cc91202fc20a44aab4c206f12a2bfe05da936051"},{"url":"https://git.kernel.org/stable/c/d970341cfa5594614c7a6634886c7688b4f5cafd"},{"url":"https://git.kernel.org/stable/c/ddc748a391dd8642ba6b2e4fe22e7f2ddf84b7f0"}],"tags":["cve.org"],"epss":0.00122,"epssPercentile":0.01816,"ingestedAt":"2026-10-21T12:48:53.651Z","slug":"CVE-2026-43036","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nnet: use skb_header_pointer() for TCPv4 GSO frag_off check\n\nSyzbot reported a KMSAN uninit-value warning in gso_features_check()\ncalled from netif_skb_features() [1].\n\ngso_features_check() reads iph->frag_off to decide whether to clear\nmangleid_features. Accessing the IPv4 header via ip_hdr()/inner_ip_hdr()\ncan rely on skb header offsets that are not always safe for direct\ndereference on packets injected from PF_PACKET paths.\n\nUse skb_header_pointer() for the TCPv4 frag_off check so the header read\nis robust whether data is already linear or needs copying.\n\n[1] https://syzkaller.appspot.com/bug?extid=1543a7d954d9c6d00407\n\n## Affected\n\n- `Linux >= cbc53e08a793b073e79f42ca33f1f3568703540d < 5057502630fbc8ce468ff617ff59af275960b537`\n- `Linux >= cbc53e08a793b073e79f42ca33f1f3568703540d < f7a6cd508e9e825a2c69fa9e13d41ee156852f25`\n- `Linux >= cbc53e08a793b073e79f42ca33f1f3568703540d < cc91202fc20a44aab4c206f12a2bfe05da936051`\n- `Linux >= cbc53e08a793b073e79f42ca33f1f3568703540d < d970341cfa5594614c7a6634886c7688b4f5cafd`\n- `Linux >= cbc53e08a793b073e79f42ca33f1f3568703540d < ddc748a391dd8642ba6b2e4fe22e7f2ddf84b7f0`\n- `Linux 4.7`\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":[]}