CVE-2025-40248

Description

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]/

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References

Other References

https://git.kernel.org/stable/c/002541ef650b742a198e4be363881439bb9d86b4 https://git.kernel.org/stable/c/3f71753935d648082a8279a97d30efe6b85be680 https://git.kernel.org/stable/c/5998da5a8208ae9ad7838ba322bccb2bdcd95e81 https://git.kernel.org/stable/c/67432915145848658149683101104e32f9fd6559 https://git.kernel.org/stable/c/ab6b19f690d89ae4709fba73a3c4a7911f495b7a https://git.kernel.org/stable/c/da664101fb4a0de5cb70d2bae6a650df954df2af https://git.kernel.org/stable/c/eeca93f06df89be5a36305b7b9dae1ed65550dfc https://git.kernel.org/stable/c/f1c170cae285e4b8f61be043bb17addc3d0a14b5

Frequently Asked Questions

What is CVE-2025-40248? +

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 do I check if I'm vulnerable to CVE-2025-40248? +

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.

CVE-2025-40248

Description

References

Other References

Frequently Asked Questions

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