CVE-2025-21669: linux kernel Null Dereference — Fix

Description

In the Linux kernel, the following vulnerability has been resolved: vsock/virtio: discard packets if the transport changes If the socket has been de-assigned or assigned to another transport, we must discard any packets received because they are not expected and would cause issues when we access vsk->transport. A possible scenario is described by Hyunwoo Kim in the attached link, where after a first connect() interrupted by a signal, and a second connect() failed, we can find `vsk->transport` at NULL, leading to a NULL pointer dereference.

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CVSS v3.1 Score

5.5

MEDIUM

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

Weakness Type (CWE)

CWE-476 CWE-476

Affected Products

Vendor	Product	Versions
linux	linux_kernel	5.5 — 5.15.177
linux	linux_kernel	5.16 — 6.1.127
linux	linux_kernel	6.2 — 6.6.74
linux	linux_kernel	6.7 — 6.12.11
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All

References

Advisories & Patches

https://git.kernel.org/stable/c/18a7fc371d1dbf8deff16c2dd9292bcc73f43040 https://git.kernel.org/stable/c/2cb7c756f605ec02ffe562fb26828e4bcc5fdfc1 https://git.kernel.org/stable/c/6486915fa661584d70e8e7e4068c6c075c67dd6d https://git.kernel.org/stable/c/677579b641af109613564460a4e3bdcb16850b61 https://git.kernel.org/stable/c/88244163bc7e7b0ce9dd7bf4c8a563b41525c3ee https://git.kernel.org/stable/c/d88b249e14bd0ee1e46bbe4f456e22e01b8c68de

Other References

https://lists.debian.org/debian-lts-announce/2025/03/msg00001.html https://lists.debian.org/debian-lts-announce/2025/03/msg00002.html https://cert-portal.siemens.com/productcert/html/ssa-265688.html

Frequently Asked Questions

What is CVE-2025-21669? +

In the Linux kernel, the following vulnerability has been resolved: vsock/virtio: discard packets if the transport changes If the socket has been de-assigned or assigned to another transport, we must discard any packets received because they are not expected and would cause issues when we access vsk->transport. A possible scenario is described by Hyunwoo Kim in the attached link, where after a first connect() interrupted by a signal, and a second connect() failed, we can find `vsk->transport` at NULL, leading to a NULL pointer dereference. It has a CVSS v3.1 base score of 5.5 (MEDIUM).

How severe is CVE-2025-21669? +

CVE-2025-21669 has a CVSS v3.1 score of 5.5 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance.

What products are affected by CVE-2025-21669? +

CVE-2025-21669 affects products from linux, specifically: linux_kernel. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2025-21669? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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