UBUNTU-CVE-2025-21854
In the Linux kernel, the following vulnerability has been resolved: sockmap, vsock: For connectible sockets allow only connected sockmap expects all vsocks to have a transport assigned, which is expressed in vsock_proto::psock_update_sk_prot(). However, there is an edge case where an unconnected (connectible) socket may lose its previously assigned transport. This is handled with a NULL check in the vsock/BPF recv path. Another design detail is that listening vsocks are not supposed to have any transport assigned at all. Which implies they are not supported by the sockmap. But this is complicated by the fact that a socket, before switching to TCP_LISTEN, may have had some transport assigned during a failed connect() attempt. Hence, we may end up with a listening vsock in a sockmap, which blows up quickly: KASAN: null-ptr-deref in range [0x0000000000000120-0x0000000000000127] CPU: 7 UID: 0 PID: 56 Comm: kworker/7:0 Not tainted 6.14.0-rc1+ Workqueue: vsock-loopback vsock_loopback_work RIP: 0010:vsock_read_skb+0x4b/0x90 Call Trace: sk_psock_verdict_data_ready+0xa4/0x2e0 virtio_transport_recv_pkt+0x1ca8/0x2acc vsock_loopback_work+0x27d/0x3f0 process_one_work+0x846/0x1420 worker_thread+0x5b3/0xf80 kthread+0x35a/0x700 ret_from_fork+0x2d/0x70 ret_from_fork_asm+0x1a/0x30 For connectible sockets, instead of relying solely on the state of vsk->transport, tell sockmap to only allow those representing established connections. This aligns with the behaviour for AF_INET and AF_UNIX.
02 / AFFECTED SOFTWARE
Affected packages
28 explicit affected versions
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37 explicit affected versions
10 explicit affected versions
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78 explicit affected versions
25 explicit affected versions
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37 explicit affected versions
8 explicit affected versions
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3 explicit affected versions
33 explicit affected versions
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19 explicit affected versions
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51 explicit affected versions
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13 explicit affected versions
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28 explicit affected versions
1 explicit affected versions
10 explicit affected versions
10 explicit affected versions
21 explicit affected versions
1 explicit affected versions
8 explicit affected versions
13 explicit affected versions
21 explicit affected versions
24 explicit affected versions
6 explicit affected versions
13 explicit affected versions
12 explicit affected versions
7 explicit affected versions
14 explicit affected versions
18 explicit affected versions
12 explicit affected versions
26 explicit affected versions
25 explicit affected versions
1 explicit affected versions
28 explicit affected versions
3 explicit affected versions
29 explicit affected versions
23 explicit affected versions
14 explicit affected versions
5 explicit affected versions
5 explicit affected versions
3 explicit affected versions
3 explicit affected versions
26 explicit affected versions
12 explicit affected versions
44 explicit affected versions
15 explicit affected versions
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4 explicit affected versions
4 explicit affected versions
16 explicit affected versions
9 explicit affected versions
23 explicit affected versions
12 explicit affected versions
4 explicit affected versions
7 explicit affected versions
13 explicit affected versions
7 explicit affected versions
31 explicit affected versions
23 explicit affected versions
5 explicit affected versions
13 explicit affected versions
32 explicit affected versions
7 explicit affected versions
10 explicit affected versions
14 explicit affected versions
18 explicit affected versions
3 explicit affected versions
16 explicit affected versions
43 explicit affected versions
11 explicit affected versions
35 explicit affected versions
12 explicit affected versions
13 explicit affected versions
21 explicit affected versions
6 explicit affected versions
12 explicit affected versions
1 explicit affected versions
50 explicit affected versions
11 explicit affected versions
12 explicit affected versions
26 explicit affected versions
27 explicit affected versions
12 explicit affected versions
7 explicit affected versions
03 / CONNECTIONS
Connected vulnerabilities
04 / EVIDENCE
Source records
In the Linux kernel, the following vulnerability has been resolved: sockmap, vsock: For connectible sockets allow only connected sockmap expects all vsocks to have a transport assigned, which is expressed in vsock_proto::psock_update_sk_prot(). However, there is an edge case where an unconnected (connectible) socket may lose its previously assigned transport. This is handled with a NULL check in the vsock/BPF recv path. Another design detail is that listening vsocks are not supposed to have any transport assigned at all. Which implies they are not supported by the sockmap. But this is complicated by the fact that a socket, before switching to TCP_LISTEN, may have had some transport assigned during a failed connect() attempt. Hence, we may end up with a listening vsock in a sockmap, which blows up quickly: KASAN: null-ptr-deref in range [0x0000000000000120-0x0000000000000127] CPU: 7 UID: 0 PID: 56 Comm: kworker/7:0 Not tainted 6.14.0-rc1+ Workqueue: vsock-loopback vsock_loopback_work RIP: 0010:vsock_read_skb+0x4b/0x90 Call Trace: sk_psock_verdict_data_ready+0xa4/0x2e0 virtio_transport_recv_pkt+0x1ca8/0x2acc vsock_loopback_work+0x27d/0x3f0 process_one_work+0x846/0x1420 worker_thread+0x5b3/0xf80 kthread+0x35a/0x700 ret_from_fork+0x2d/0x70 ret_from_fork_asm+0x1a/0x30 For connectible sockets, instead of relying solely on the state of vsk->transport, tell sockmap to only allow those representing established connections. This aligns with the behaviour for AF_INET and AF_UNIX.
05 / REFERENCES
Further evidence
- https://git.kernel.org/linus/8fb5bb169d17cdd12c2dcc2e96830ed487d77a0f
- https://git.kernel.org/stable/c/22b683217ad2112791a708693cb236507abd637a
- https://git.kernel.org/stable/c/8fb5bb169d17cdd12c2dcc2e96830ed487d77a0f
- https://git.kernel.org/stable/c/cc9a7832ede53ade1ba9991f0e27314caa4029d8
- https://git.kernel.org/stable/c/f7b473e35986835cc2813fef7b9d40336a09247e
- https://ubuntu.com/security/CVE-2025-21854
- https://ubuntu.com/security/notices/USN-7521-1
- https://ubuntu.com/security/notices/USN-7521-2
- https://ubuntu.com/security/notices/USN-7521-3
- https://ubuntu.com/security/notices/USN-7703-1
- https://ubuntu.com/security/notices/USN-7703-2
- https://ubuntu.com/security/notices/USN-7703-3
- https://ubuntu.com/security/notices/USN-7703-4
- https://ubuntu.com/security/notices/USN-7719-1
- https://ubuntu.com/security/notices/USN-7737-1
- https://www.cve.org/CVERecord?id=CVE-2025-21854