{ "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" } } } }