CVE-2025-21864

MEDIUM EPSS 10.0%
Published Mar 12, 20251y ago · Modified Jun 17, 20261w ago
5.5 CVSS 3.1
Medium
Find Similar
Published Mar 12, 2025 1y ago
Last Modified Jun 17, 2026 1w ago

Description

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 Details

Base Score
5.5
Exploitability
1.8
Impact
3.6
Vector string
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Attack Vector Local
Attack Complexity Low
Privileges Required Low
User Interaction None
Scope Unchanged
Confidentiality None
Integrity None
Availability High

Threat Intelligence

EPSS Exploit Probability
10.0% percentile
Exploit & Patch Status
No Known Exploit
Patch Available

Weaknesses 1

CWE-476 NULL Pointer Dereference Memory Safety

Affected Products 7

VendorProductVersionRange
linuxlinux_kernel*≥5.19  –  <6.1.130
linuxlinux_kernel*≥6.2  –  <6.6.80
linuxlinux_kernel*≥6.7  –  <6.12.17
linuxlinux_kernel*≥6.13  –  <6.13.5
linuxlinux_kernel6.14any
linuxlinux_kernel6.14any
linuxlinux_kernel6.14any

References 7

  • cert-portal.siemens.com https://cert-portal.siemens.com/productcert/html/ssa-082556.html
  • git.kernel.org https://git.kernel.org/stable/c/69cafd9413084cd5012cf5d7c7ec6f3d493726d9
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/87858bbf21da239ace300d61dd209907995c0491
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/9b6412e6979f6f9e0632075f8f008937b5cd4efd
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/cd34a07f744451e2ecf9005bb7d24d0b2fb83656
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/f1d5e6a5e468308af7759cf5276779d3155c5e98
    Patch
  • lists.debian.org https://lists.debian.org/debian-lts-announce/2025/05/msg00045.html

Remediation

  • git.kernel.org https://git.kernel.org/stable/c/69cafd9413084cd5012cf5d7c7ec6f3d493726d9
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/87858bbf21da239ace300d61dd209907995c0491
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/9b6412e6979f6f9e0632075f8f008937b5cd4efd
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/cd34a07f744451e2ecf9005bb7d24d0b2fb83656
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/f1d5e6a5e468308af7759cf5276779d3155c5e98
    Patch