🛡️ CVE-2025-40248 — kernel

🟠 CVSS 7.8 — High ✅ No Known Exploit NVD
7.8
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

vsock: Ignore signal/timeout on connect() if already established

In the Linux kernel, the following vulnerability has been resolved:

vsock: Ignore signal/timeout on connect() if already established

During connect(), acting on a signal/timeout by disconnecting an already

established socket leads to several issues:

1. connect() invoking vsock_transport_cancel_pkt() ->

virtio_transport_purge_skbs() may race with sendmsg() invoking

virtio_transport_get_credit(). This results in a permanently elevated

vvs->bytes_unsent. Which, in turn, confuses the SOCK_LINGER handling.

2. connect() resetting a connected socket's state may race with socket

being placed in a sockmap. A disconnected socket remaining in a sockmap

breaks sockmap's assumptions. And gives rise to WARNs.

3. connect() transitioning SS_CONNECTED -> SS_UNCONNECTED allows for a

transport change/drop after TCP_ESTABLISHED. Which poses a problem for

any simultaneous sendmsg() or connect() and may result in a

use-after-free/null-ptr-deref.

Do not disconnect socket on signal/timeout. Keep the logic for unconnected

sockets: they don't linger, can't be placed in a sockmap, are rejected by

sendmsg().

[1]: https://lore.kernel.org/netdev/[email protected]/

[2]: https://lore.kernel.org/netdev/[email protected]/

[3]: https://lore.kernel.org/netdev/[email protected]/

How this vulnerability can be exploited

This issue can be reached with local access to the system, attack complexity is low, an attacker needs low-level privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality high, integrity high, availability high.

Affected software

CVE-2025-40248 is recorded against 2 packages.

  • kernel (from 6.13.0 up to 6.17.10)
  • unknown

Timeline and source

Published on 4 December 2025 and last revised on 6 August 2026. No public exploit is currently recorded for this entry. Record sourced from NVD.

References

cert-portal.siemens.com (Web)
git.kernel.org (Web)
git.kernel.org (Web)
git.kernel.org (Web)
git.kernel.org (Web)
git.kernel.org (Web)
git.kernel.org (Web)
git.kernel.org (Web)
git.kernel.org (Web)
github.com (Advisory)
nvd.nist.gov (Advisory)
git.kernel.org (Package)

CVE-2025-40248 on other distributions

Each distribution ships its own build and its own fixed version. Pick the one you run:

Details

Severity High
CVSS Score 7.8
CVSS Vector CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CWE N/A
Public Exploit ✅ No
Source NVD
Published 2025-12-04
Updated 2026-08-12
Modified 2026-08-06
Fix URL N/A

Affected Packages

Software From version Fixed in
kernel 6.13.0 6.17.10
unknown — —

References

Similar Threats

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