netfilter: nf_nat_sip: reload possible stale data pointer

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-72251
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-15 06:21:52 UTC
Updated2026-08-17 06:18:27 UTC
DescriptionIn 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 and header corruption involving the SIP NAT helper. In net/netfilter/nf_nat_sip.c:nf_nat_sip(): if (skb_ensure_writable(skb, skb->len)) { nf_ct_helper_log(skb, ct, "cannot mangle packet"); return NF_DROP; } uh = (void *)skb->data + protoff; uh->dest = ct_sip_info->forced_dport; if (!nf_nat_mangle_udp_packet(skb, ct, ctinfo, protoff, 0, 0, NULL, 0)) { If a cloned or fragmented SKB is reallocated by skb_ensure_writable(), the old data buffer is freed. However, nf_nat_sip() fails to update *dptr to point to the new buffer. It also appears to use nf_nat_mangle_udp_packet() on what could be a TCP packet, which would overwrite the sequence number with a checksum update. ------------------------------------------------------------------------ nf_conntrack_sip linerizes skbs, hence no fragmented skb can be seen. But clones are possible, so rebuild dptr. Disable nf_nat_mangle_udp_packet() branch for TCP streams. It doesn't look like this can ever happen, else we should have received bug reports about this, so just check the conntrack is UDP and drop otherwise. The calling conntrack_sip set ->forced_dport for SIP_HDR_VIA_UDP messages, so I don't think this is ever expected to be true for a TCP stream.

Risk And Classification

Primary CVSS: v3.1 9.8 CRITICAL from 416baaa9-dc9f-4396-8d5f-8c081fb06d67

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS: 0.007040000 probability, percentile 0.502740000 (date 2026-08-17)

VersionSourceTypeScoreSeverityVector
3.1416baaa9-dc9f-4396-8d5f-8c081fb06d67Secondary9.8CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
3.1CNADECLARED9.8CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 7266507d89991fa1e989283e4e032c6d9357fe26 bded21a4bf9bf86a79148be735723a97ca9a7532 git Not specified
CNA Linux Linux affected 7266507d89991fa1e989283e4e032c6d9357fe26 dc11f26685aa850f237226f0f463647aea58ab7c git Not specified
CNA Linux Linux affected 7266507d89991fa1e989283e4e032c6d9357fe26 e38143c9b477f2968024c47c647dd4456a40aff1 git Not specified
CNA Linux Linux affected 7266507d89991fa1e989283e4e032c6d9357fe26 57e4e29644ec054d7021d296407e7ddd844afea2 git Not specified
CNA Linux Linux affected 7266507d89991fa1e989283e4e032c6d9357fe26 eae9c6ccb5af69c713a65f8ae219f5c1aa32cd17 git Not specified
CNA Linux Linux affected 7266507d89991fa1e989283e4e032c6d9357fe26 2bcf2c5052fb5e73e255140ab43f056aef409c27 git Not specified
CNA Linux Linux affected 7266507d89991fa1e989283e4e032c6d9357fe26 0e76e3e886cc9ee027337d5ad39cb96f57b7bdc7 git Not specified
CNA Linux Linux affected 7266507d89991fa1e989283e4e032c6d9357fe26 77e43bcb7ec177e293a5c3f1b91a2c5aebfb6c68 git Not specified
CNA Linux Linux affected 3.9 Not specified
CNA Linux Linux unaffected 3.9 semver Not specified
CNA Linux Linux unaffected 5.10.261 5.10.* semver Not specified
CNA Linux Linux unaffected 5.15.212 5.15.* semver Not specified
CNA Linux Linux unaffected 6.1.178 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.145 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.97 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.40 6.18.* semver Not specified
CNA Linux Linux unaffected 7.1.5 7.1.* semver Not specified
CNA Linux Linux unaffected 7.2 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/eae9c6ccb5af69c713a65f8ae219f5c1aa32cd17 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/dc11f26685aa850f237226f0f463647aea58ab7c 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/2bcf2c5052fb5e73e255140ab43f056aef409c27 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/77e43bcb7ec177e293a5c3f1b91a2c5aebfb6c68 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/bded21a4bf9bf86a79148be735723a97ca9a7532 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/57e4e29644ec054d7021d296407e7ddd844afea2 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/e38143c9b477f2968024c47c647dd4456a40aff1 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/0e76e3e886cc9ee027337d5ad39cb96f57b7bdc7 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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