Linux kernel vsock: TCP_CLOSING handling & memory corruption (CVE-2026-99213)
CVE-2026-99213 Published on October 28, 2026
vsock: treat TCP_CLOSING as once-established
In the Linux kernel, the following vulnerability has been resolved:
vsock: treat TCP_CLOSING as once-established
Handle the TCP_ESTABLISHED -> TCP_CLOSING transition on OP_RST, which can
race with the connect loop. Immediately break and return 0 on
ESTABLISHED/CLOSING. The return value of connect() should reflect what
happened up to the point the connection was established or failed. Events
that occur afterwards must not affect it. E.g. even if OP_RW has already
set sk_err, connect() should still return 0, not ENOBUFS because of it.
Adapt the inaccurate comment above signal_pending().
Resetting a socket that is still present in connected_table can lead to
memory corruption. The reporter noted lost transports for in-flight skbs,
and I have reproduced crashes caused by re-insertion into connected_table.
list_add double add: new=, prev=, next=.
kernel BUG at lib/list_debug.c:35!
Oops: invalid opcode: 0000 [#1] SMP KASAN NOPTI
Workqueue: vsock-loopback vsock_loopback_work
RIP: 0010:__list_add_valid_or_report+0x11f/0x130
Call Trace:
vsock_insert_connected.cold+0xe/0x13
virtio_transport_recv_pkt+0x10e9/0x1460
vsock_loopback_work+0x305/0x480
process_one_work+0xe4c/0x1560
worker_thread+0x4f1/0xd60
kthread+0x36e/0x470
ret_from_fork+0x47b/0x6b0
ret_from_fork_asm+0x1a/0x30
This fix is supplementary to commit 002541ef650b ("vsock: Ignore
signal/timeout on connect() if already established"). Details under Link.
Products Associated with CVE-2026-99213
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Affected Versions
Linux:- Version d021c344051af91f42c5ba9fdedc176740cbd238 and below c2c5359ef2c33684fa3f3652fd761a483db8d1e7 is affected.
- Version d021c344051af91f42c5ba9fdedc176740cbd238 and below 44d1ca05d6094a5d75c671a0545249186d790b8d is affected.
- Version d021c344051af91f42c5ba9fdedc176740cbd238 and below 4f6ac74fa594a918d41255c941256e1d51592d3b is affected.
- Version 3.9 is affected.
- Before 3.9 is unaffected.
- Version 6.18.59, <= 6.18.* is unaffected.
- Version 7.2.13, <= 7.2.* is unaffected.
- Version 7.3, <= * is unaffected.