{"api_version":"1","generated_at":"2026-08-22T02:57:02+00:00","cve":"CVE-2026-72251","urls":{"html":"https://cve.report/CVE-2026-72251","api":"https://cve.report/api/cve/CVE-2026-72251.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-72251","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-72251"},"summary":{"title":"netfilter: nf_nat_sip: reload possible stale data pointer","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.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-08-15 06:21:52","updated_at":"2026-08-17 06:18:27"},"problem_types":[],"metrics":[{"version":"3.1","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","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","data":{"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","attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"}},{"version":"3.1","source":"CNA","type":"DECLARED","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","data":{"baseScore":9.8,"baseSeverity":"CRITICAL","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","version":"3.1"}}],"references":[{"url":"https://git.kernel.org/stable/c/eae9c6ccb5af69c713a65f8ae219f5c1aa32cd17","name":"https://git.kernel.org/stable/c/eae9c6ccb5af69c713a65f8ae219f5c1aa32cd17","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/dc11f26685aa850f237226f0f463647aea58ab7c","name":"https://git.kernel.org/stable/c/dc11f26685aa850f237226f0f463647aea58ab7c","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/2bcf2c5052fb5e73e255140ab43f056aef409c27","name":"https://git.kernel.org/stable/c/2bcf2c5052fb5e73e255140ab43f056aef409c27","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/77e43bcb7ec177e293a5c3f1b91a2c5aebfb6c68","name":"https://git.kernel.org/stable/c/77e43bcb7ec177e293a5c3f1b91a2c5aebfb6c68","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/bded21a4bf9bf86a79148be735723a97ca9a7532","name":"https://git.kernel.org/stable/c/bded21a4bf9bf86a79148be735723a97ca9a7532","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/57e4e29644ec054d7021d296407e7ddd844afea2","name":"https://git.kernel.org/stable/c/57e4e29644ec054d7021d296407e7ddd844afea2","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/e38143c9b477f2968024c47c647dd4456a40aff1","name":"https://git.kernel.org/stable/c/e38143c9b477f2968024c47c647dd4456a40aff1","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/0e76e3e886cc9ee027337d5ad39cb96f57b7bdc7","name":"https://git.kernel.org/stable/c/0e76e3e886cc9ee027337d5ad39cb96f57b7bdc7","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-72251","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-72251","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 7266507d89991fa1e989283e4e032c6d9357fe26 bded21a4bf9bf86a79148be735723a97ca9a7532 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 7266507d89991fa1e989283e4e032c6d9357fe26 dc11f26685aa850f237226f0f463647aea58ab7c git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 7266507d89991fa1e989283e4e032c6d9357fe26 e38143c9b477f2968024c47c647dd4456a40aff1 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 7266507d89991fa1e989283e4e032c6d9357fe26 57e4e29644ec054d7021d296407e7ddd844afea2 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 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semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 5.15.212 5.15.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.1.178 6.1.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.6.145 6.6.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.12.97 6.12.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.40 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.1.5 7.1.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":{"cve_year":"2026","cve_id":"72251","cve":"CVE-2026-72251","epss":"0.007040000","percentile":"0.502740000","score_date":"2026-08-17","updated_at":"2026-08-18 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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":{"baseScore":9.8,"baseSeverity":"CRITICAL","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","version":"3.1"},"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."}]}],"providerMetadata":{"dateUpdated":"2026-08-17T05:42:03.339Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"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"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-72251","datePublished":"2026-08-15T05:54:39.983Z","dateReserved":"2026-08-09T03:40:39.915Z","dateUpdated":"2026-08-17T05:42:03.339Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-08-15 06:21:52","lastModifiedDate":"2026-08-17 06:18:27","problem_types":[],"metrics":{"cvssMetricV31":[{"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","cvssData":{"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","attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"},"exploitabilityScore":3.9,"impactScore":5.9}]},"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"72251","Ordinal":"1","Title":"netfilter: nf_nat_sip: reload possible stale data pointer","CVE":"CVE-2026-72251","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"72251","Ordinal":"1","NoteData":"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.","Type":"Description","Title":"netfilter: nf_nat_sip: reload possible stale data pointer"}]}}}