tcp: drop secpath at the same time as we currently drop dst

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Summary

CVECVE-2025-21864
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2025-03-12 10:15:19 UTC
Updated2026-07-14 13:17:25 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: tcp: drop secpath at the same time as we currently drop dst Xiumei reported hitting the WARN in xfrm6_tunnel_net_exit while running tests that boil down to: - create a pair of netns - run a basic TCP test over ipcomp6 - delete the pair of netns The xfrm_state found on spi_byaddr was not deleted at the time we delete the netns, because we still have a reference on it. This lingering reference comes from a secpath (which holds a ref on the xfrm_state), which is still attached to an skb. This skb is not leaked, it ends up on sk_receive_queue and then gets defer-free'd by skb_attempt_defer_free. The problem happens when we defer freeing an skb (push it on one CPU's defer_list), and don't flush that list before the netns is deleted. In that case, we still have a reference on the xfrm_state that we don't expect at this point. We already drop the skb's dst in the TCP receive path when it's no longer needed, so let's also drop the secpath. At this point, tcp_filter has already called into the LSM hooks that may require the secpath, so it should not be needed anymore. However, in some of those places, the MPTCP extension has just been attached to the skb, so we cannot simply drop all extensions.

Risk And Classification

Primary CVSS: v3.1 5.5 MEDIUM from [email protected]

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

Problem Types: CWE-476 | CWE-476 CWE-476 NULL Pointer Dereference

VersionSourceTypeScoreSeverityVector
3.1[email protected]Primary5.5MEDIUMCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
3.1ADPDECLARED5.5MEDIUMCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
3.1134c704f-9b21-4f2e-91b3-4a467353bcc0Secondary5.5MEDIUMCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

CVSS v3.1 Breakdown

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

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

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Operating System Linux Linux Kernel All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 68822bdf76f10c3dc80609d4e2cdc1e847429086 87858bbf21da239ace300d61dd209907995c0491 git Not specified
CNA Linux Linux affected 68822bdf76f10c3dc80609d4e2cdc1e847429086 f1d5e6a5e468308af7759cf5276779d3155c5e98 git Not specified
CNA Linux Linux affected 68822bdf76f10c3dc80609d4e2cdc1e847429086 cd34a07f744451e2ecf9005bb7d24d0b2fb83656 git Not specified
CNA Linux Linux affected 68822bdf76f10c3dc80609d4e2cdc1e847429086 69cafd9413084cd5012cf5d7c7ec6f3d493726d9 git Not specified
CNA Linux Linux affected 68822bdf76f10c3dc80609d4e2cdc1e847429086 9b6412e6979f6f9e0632075f8f008937b5cd4efd git Not specified
CNA Linux Linux affected 5.19 Not specified
CNA Linux Linux unaffected 5.19 semver Not specified
CNA Linux Linux unaffected 6.1.130 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.80 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.17 6.12.* semver Not specified
CNA Linux Linux unaffected 6.13.5 6.13.* semver Not specified
CNA Linux Linux unaffected 6.14 * original_commit_for_fix Not specified
ADP Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP affected V3.1.5 * custom Not specified
ADP Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP affected V3.1.6 * custom Not specified
ADP Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP affected V3.1.5 * custom Not specified
ADP Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP affected V3.1.6 * custom Not specified
ADP Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP affected V3.1.5 * custom Not specified
ADP Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP affected V3.1.6 * custom Not specified
ADP Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP affected V3.1.5 * custom Not specified
ADP Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP affected V3.1.6 * custom Not specified
ADP Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP affected V3.1.5 * custom Not specified
ADP Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP affected V3.1.6 * custom Not specified

References

ReferenceSourceLinkTags
cert-portal.siemens.com/productcert/html/ssa-082556.html 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e cert-portal.siemens.com
git.kernel.org/stable/c/f1d5e6a5e468308af7759cf5276779d3155c5e98 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/69cafd9413084cd5012cf5d7c7ec6f3d493726d9 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
cert-portal.siemens.com/productcert/html/ssa-019113.html 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e cert-portal.siemens.com
git.kernel.org/stable/c/9b6412e6979f6f9e0632075f8f008937b5cd4efd 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
lists.debian.org/debian-lts-announce/2025/05/msg00045.html af854a3a-2127-422b-91ae-364da2661108 lists.debian.org
git.kernel.org/stable/c/87858bbf21da239ace300d61dd209907995c0491 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/cd34a07f744451e2ecf9005bb7d24d0b2fb83656 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
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