vulnerability

Amazon Linux 2023: CVE-2025-40248: Important priority package update for kernel

Severity
7
CVSS
(AV:L/AC:M/Au:S/C:C/I:C/A:C)
Published
Dec 4, 2025
Added
Jan 12, 2026
Modified
Jan 12, 2026

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]/

Solutions

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