{"id":"CVE-2026-72251","title":"netfilter: nf_nat_sip: reload possible stale data pointer","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: nf_nat_sip: reload possible stale data pointer\n\nquoting sashiko:\n ------------------------------------------------------------------------\n [..] noticed a po…","severity":"critical","cvss":9.8,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","cvssSource":"cna","vendor":"Linux","product":"Linux","affected":["Linux >= 7266507d89991fa1e989283e4e032c6d9357fe26 < bded21a4bf9bf86a79148be735723a97ca9a7532","Linux >= 7266507d89991fa1e989283e4e032c6d9357fe26 < dc11f26685aa850f237226f0f463647aea58ab7c","Linux >= 7266507d89991fa1e989283e4e032c6d9357fe26 < e38143c9b477f2968024c47c647dd4456a40aff1","Linux >= 7266507d89991fa1e989283e4e032c6d9357fe26 < 57e4e29644ec054d7021d296407e7ddd844afea2","Linux >= 7266507d89991fa1e989283e4e032c6d9357fe26 < eae9c6ccb5af69c713a65f8ae219f5c1aa32cd17","Linux >= 7266507d89991fa1e989283e4e032c6d9357fe26 < 2bcf2c5052fb5e73e255140ab43f056aef409c27","Linux >= 7266507d89991fa1e989283e4e032c6d9357fe26 < 0e76e3e886cc9ee027337d5ad39cb96f57b7bdc7","Linux >= 7266507d89991fa1e989283e4e032c6d9357fe26 < 77e43bcb7ec177e293a5c3f1b91a2c5aebfb6c68","Linux 3.9"],"ssvc":{"exploitation":"none","automatable":"yes","technicalImpact":"total","timestamp":"2026-10-16T18:45:12.402575Z"},"published":"2026-08-15","updated":"2026-10-16","sourceUpdated":"2026-10-16T18:55:13.187Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-72251","references":[{"url":"https://git.kernel.org/stable/c/bded21a4bf9bf86a79148be735723a97ca9a7532"},{"url":"https://git.kernel.org/stable/c/dc11f26685aa850f237226f0f463647aea58ab7c"},{"url":"https://git.kernel.org/stable/c/e38143c9b477f2968024c47c647dd4456a40aff1"},{"url":"https://git.kernel.org/stable/c/57e4e29644ec054d7021d296407e7ddd844afea2"},{"url":"https://git.kernel.org/stable/c/eae9c6ccb5af69c713a65f8ae219f5c1aa32cd17"},{"url":"https://git.kernel.org/stable/c/2bcf2c5052fb5e73e255140ab43f056aef409c27"},{"url":"https://git.kernel.org/stable/c/0e76e3e886cc9ee027337d5ad39cb96f57b7bdc7"},{"url":"https://git.kernel.org/stable/c/77e43bcb7ec177e293a5c3f1b91a2c5aebfb6c68"}],"tags":["cve.org"],"epss":0.00714,"epssPercentile":0.52759,"ingestedAt":"2026-10-16T19:46:24.416Z","slug":"CVE-2026-72251","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: nf_nat_sip: reload possible stale data pointer\n\nquoting sashiko:\n ------------------------------------------------------------------------\n [..] noticed a potential memory bug and header corruption involving the\n SIP NAT helper.\n\n In net/netfilter/nf_nat_sip.c:nf_nat_sip():\n\tif (skb_ensure_writable(skb, skb->len)) {\n\t\tnf_ct_helper_log(skb, ct, \"cannot mangle packet\");\n\t\treturn NF_DROP;\n\t}\n\tuh = (void *)skb->data + protoff;\n\tuh->dest = ct_sip_info->forced_dport;\n\tif (!nf_nat_mangle_udp_packet(skb, ct, ctinfo, protoff,\n\t\t\t\t      0, 0, NULL, 0)) {\n\n If a cloned or fragmented SKB is reallocated by skb_ensure_writable(), the\n old data buffer is freed. However, nf_nat_sip() fails to update *dptr to\n point to the new buffer.\n\n It also appears to use nf_nat_mangle_udp_packet() on what could be a TCP\n packet, which would overwrite the sequence number with a checksum update.\n ------------------------------------------------------------------------\n\nnf_conntrack_sip linerizes skbs, hence no fragmented skb can be seen.\nBut clones are possible, so rebuild dptr.\n\nDisable nf_nat_mangle_udp_packet() branch for TCP streams.\nIt doesn't look like this can ever happen, else we should have received\nbug reports about this, so just check the conntrack is UDP and drop\notherwise.\n\nThe calling conntrack_sip set ->forced_dport for SIP_HDR_VIA_UDP messages,\nso I don't think this is ever expected to be true for a TCP stream.\n\n## Affected\n\n- `Linux >= 7266507d89991fa1e989283e4e032c6d9357fe26 < bded21a4bf9bf86a79148be735723a97ca9a7532`\n- `Linux >= 7266507d89991fa1e989283e4e032c6d9357fe26 < dc11f26685aa850f237226f0f463647aea58ab7c`\n- `Linux >= 7266507d89991fa1e989283e4e032c6d9357fe26 < e38143c9b477f2968024c47c647dd4456a40aff1`\n- `Linux >= 7266507d89991fa1e989283e4e032c6d9357fe26 < 57e4e29644ec054d7021d296407e7ddd844afea2`\n- `Linux >= 7266507d89991fa1e989283e4e032c6d9357fe26 < eae9c6ccb5af69c713a65f8ae219f5c1aa32cd17`\n- `Linux >= 7266507d89991fa1e989283e4e032c6d9357fe26 < 2bcf2c5052fb5e73e255140ab43f056aef409c27`\n- `Linux >= 7266507d89991fa1e989283e4e032c6d9357fe26 < 0e76e3e886cc9ee027337d5ad39cb96f57b7bdc7`\n- `Linux >= 7266507d89991fa1e989283e4e032c6d9357fe26 < 77e43bcb7ec177e293a5c3f1b91a2c5aebfb6c68`\n- `Linux 3.9`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"midnight","depthScore":54,"depthScoreParts":{"impact":53.9,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}