{"id":"CVE-2026-72251","url":"https://www.cyber-defence.io/tools/cve/CVE-2026-72251","generatedAt":"2026-10-27T23:10:12.936Z","title":"In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_nat_sip: reload possible stale data pointer quoting sashiko: ------------------------------------------------------------------------ [..] noticed a potential memory bug…","description":"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 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.","published":"2026-08-15T06:21:52.000Z","lastModified":"2026-10-16T19:17:17.000Z","status":"Received","sourceIdentifier":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","cvss":{"version":"3.1","score":9.8,"severity":"CRITICAL","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"},"cwe":[],"affected":[],"epss":{"score":0.00714,"percentile":0.53403,"date":"2026-10-26","history":[]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"high","text":"High impact if exploited, but EPSS currently rates exploitation as unlikely (0.71%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit."},"changes":[],"references":[{"url":"https://git.kernel.org/stable/c/0e76e3e886cc9ee027337d5ad39cb96f57b7bdc7","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/2bcf2c5052fb5e73e255140ab43f056aef409c27","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/57e4e29644ec054d7021d296407e7ddd844afea2","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/77e43bcb7ec177e293a5c3f1b91a2c5aebfb6c68","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/bded21a4bf9bf86a79148be735723a97ca9a7532","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/dc11f26685aa850f237226f0f463647aea58ab7c","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/e38143c9b477f2968024c47c647dd4456a40aff1","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/eae9c6ccb5af69c713a65f8ae219f5c1aa32cd17","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-72251","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}