{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-72251","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2026-08-09T03:40:39.915Z","datePublished":"2026-08-15T05:54:39.983Z","dateUpdated":"2026-08-17T05:42:03.339Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-08-17T05:42:03.339Z"},"descriptions":[{"lang":"en","value":"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."}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","baseScore":9.8,"baseSeverity":"CRITICAL"},"scenarios":[{"lang":"en","value":"AV:N - The bug is hit in nf_nat_sip() from sip_help_udp/tcp() during nf_confirm() on POST_ROUTING/LOCAL_IN while processing attacker-supplied SIP/UDP or SIP/TCP packets traversing a netfilter NAT gateway, so exploitation is via remote network traffic rather than local syscalls or physical access.\nAC:L - Once nf_conntrack_sip and nf_nat_sip are active on a NATed SIP flow, a remote peer can set forced_dport with a crafted Via header and drive the reply-path skb_ensure_writable() reallocation on cloned skbs without races or rare layout luck.\nPR:N - Exploitation needs no privileges on the victim kernel; a remote SIP endpoint only has to send malicious SIP through an already-configured SIP conntrack/NAT helper, with no authentication or local access to the firewall or router.\nUI:N - No victim user action is required beyond normal automated packet forwarding; the SIP helper parses and NAT-rewrites attacker-supplied SIP data in softirq during connection-tracking confirmation without opening files, clicking links, or mounting filesystems.\nS:U - Impact stays within kernel netfilter/conntrack memory on the same security authority (for example a NAT firewall, SBC, or VoIP gateway). This is standard kernel memory corruption, not a VM escape, sandbox breakout, or cross-tenant boundary violation.\nC:H - skb_ensure_writable() can free the old linear buffer while *dptr still points into it; sip_help_tcp() then continues parsing with that stale pointer, giving a use-after-free read of freed skb data and enabling disclosure of adjacent kernel heap contents.\nI:H - The stale dptr UAF and, on TCP flows, mistaken nf_nat_mangle_udp_packet() header rewriting corrupt kernel packet-buffer memory; such heap corruption is exploitable with grooming for arbitrary writes, control-flow hijacking, and kernel code execution.\nA:H - Use-after-free and mis-mangled L4 headers during softirq SIP NAT processing can trigger kernel oops/panic or reliably drop or corrupt in-flight VoIP signaling, causing high availability impact on internet-facing NAT/SBC systems handling SIP."}]}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/netfilter/nf_nat_sip.c"],"versions":[{"version":"7266507d89991fa1e989283e4e032c6d9357fe26","lessThan":"bded21a4bf9bf86a79148be735723a97ca9a7532","status":"affected","versionType":"git"},{"version":"7266507d89991fa1e989283e4e032c6d9357fe26","lessThan":"dc11f26685aa850f237226f0f463647aea58ab7c","status":"affected","versionType":"git"},{"version":"7266507d89991fa1e989283e4e032c6d9357fe26","lessThan":"e38143c9b477f2968024c47c647dd4456a40aff1","status":"affected","versionType":"git"},{"version":"7266507d89991fa1e989283e4e032c6d9357fe26","lessThan":"57e4e29644ec054d7021d296407e7ddd844afea2","status":"affected","versionType":"git"},{"version":"7266507d89991fa1e989283e4e032c6d9357fe26","lessThan":"eae9c6ccb5af69c713a65f8ae219f5c1aa32cd17","status":"affected","versionType":"git"},{"version":"7266507d89991fa1e989283e4e032c6d9357fe26","lessThan":"2bcf2c5052fb5e73e255140ab43f056aef409c27","status":"affected","versionType":"git"},{"version":"7266507d89991fa1e989283e4e032c6d9357fe26","lessThan":"0e76e3e886cc9ee027337d5ad39cb96f57b7bdc7","status":"affected","versionType":"git"},{"version":"7266507d89991fa1e989283e4e032c6d9357fe26","lessThan":"77e43bcb7ec177e293a5c3f1b91a2c5aebfb6c68","status":"affected","versionType":"git"}]},{"product":"Linux","vendor":"Linux","defaultStatus":"affected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/netfilter/nf_nat_sip.c"],"versions":[{"version":"3.9","status":"affected"},{"version":"0","lessThan":"3.9","status":"unaffected","versionType":"semver"},{"version":"5.10.261","lessThanOrEqual":"5.10.*","status":"unaffected","versionType":"semver"},{"version":"5.15.212","lessThanOrEqual":"5.15.*","status":"unaffected","versionType":"semver"},{"version":"6.1.178","lessThanOrEqual":"6.1.*","status":"unaffected","versionType":"semver"},{"version":"6.6.145","lessThanOrEqual":"6.6.*","status":"unaffected","versionType":"semver"},{"version":"6.12.97","lessThanOrEqual":"6.12.*","status":"unaffected","versionType":"semver"},{"version":"6.18.40","lessThanOrEqual":"6.18.*","status":"unaffected","versionType":"semver"},{"version":"7.1.5","lessThanOrEqual":"7.1.*","status":"unaffected","versionType":"semver"},{"version":"7.2","lessThanOrEqual":"*","status":"unaffected","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.9","versionEndExcluding":"5.10.261"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.9","versionEndExcluding":"5.15.212"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.9","versionEndExcluding":"6.1.178"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.9","versionEndExcluding":"6.6.145"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.9","versionEndExcluding":"6.12.97"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.9","versionEndExcluding":"6.18.40"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.9","versionEndExcluding":"7.1.5"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.9","versionEndExcluding":"7.2"}]}]}],"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"}],"title":"netfilter: nf_nat_sip: reload possible stale data pointer","x_generator":{"engine":"bippy-1.2.0"}}}}