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Unrated severityNVD Advisory· Published Dec 4, 2025· Updated Jun 2, 2026

CVE-2025-40248

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/e07fd95c-9a38-4eea-9638-133e38c2ec9b@rbox.co/ [2]: https://lore.kernel.org/netdev/20250317-vsock-trans-signal-race-v4-0-fc8837f3f1d4@rbox.co/ [3]: https://lore.kernel.org/netdev/60f1b7db-3099-4f6a-875e-af9f6ef194f6@rbox.co/

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