CVE-2025-21864tcp: drop secpath at the same time as we currently drop dst
Updated under an hour ago ()
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It affects Linux and 5 other products. Add what you run to find out whether that includes you.
No exploitation reported and no EPSS estimate yet.
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In 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.
- CVSS
- 7.8 HIGH (v3.1, CNA)CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- Weakness (CWE)
- CWE-476
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- Linux
- NVD analysis
- Modified
- Record last updated
- Oct 15, 2026
- First seen by InfoSec Signals
- Oct 15, 2026
Affected products
Linux Linux linux:linux (from the name) | from 68822bdf76f10c3dc80609d4e2cdc1e847429086 before 87858bbf21da239ace300d61dd209907995c0491; from 68822bdf76f10c3dc80609d4e2cdc1e847429086 before f1d5e6a5e468308af7759cf5276779d3155c5e98; from 68822bdf76f10c3dc80609d4e2cdc1e847429086 before cd34a07f744451e2ecf9005bb7d24d0b2fb83656; 68822bdf76f10c3dc80609d4e2cdc1e847429086 builds before 69cafd9413084cd5012cf5d7c7ec6f3d493726d9; 68822bdf76f10c3dc80609d4e2cdc1e847429086 builds before 9b6412e6979f6f9e0632075f8f008937b5cd4efd | CNA record |
Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP siemens:simatic_s7_1500_cpu_1518_4_pn_dp_mfp (from the name) | from V3.1.5 | CISA ADP |
Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP siemens:simatic_s7_1500_cpu_1518f_4_pn_dp_mfp (from the name) | from V3.1.5 | CISA ADP |
Siemens SIMATIC S7-1500 TM MFP - GNU/Linux subsystem siemens:simatic_s7_1500_tm_mfp_gnu_linux_subsystem (from the name) | all versions | CISA ADP |
Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP siemens:siplus_s7_1500_cpu_1518_4_pn_dp_mfp (from the name) | from V3.1.5 | CISA ADP |
linux linux_kernel linux:linux_kernel | from 5.19 before 6.1.130; from 6.2 before 6.6.80; from 6.7 before 6.12.17; from 6.13 before 6.13.5; 6.14; 6.14; 6.14 | NVD |
References
- https://git.kernel.org/stable/c/87858bbf21da239ace300d61dd209907995c0491patch
- https://git.kernel.org/stable/c/f1d5e6a5e468308af7759cf5276779d3155c5e98patch
- https://git.kernel.org/stable/c/cd34a07f744451e2ecf9005bb7d24d0b2fb83656patch
- https://git.kernel.org/stable/c/69cafd9413084cd5012cf5d7c7ec6f3d493726d9patch
- https://git.kernel.org/stable/c/9b6412e6979f6f9e0632075f8f008937b5cd4efdpatch
- https://lists.debian.org/debian-lts-announce/2025/05/msg00045.html
- https://cert-portal.siemens.com/productcert/html/ssa-019113.html
- https://cert-portal.siemens.com/productcert/html/ssa-082556.html
- https://cert-portal.siemens.com/productcert/html/ssa-457936.html
- https://cert-portal.siemens.com/productcert/html/ssa-784472.html
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.