UBUNTU-CVE-2025-39682
In the Linux kernel, the following vulnerability has been resolved: tls: fix handling of zero-length records on the rx_list Each recvmsg() call must process either - only contiguous DATA records (any number of them) - one non-DATA record If the next record has different type than what has already been processed we break out of the main processing loop. If the record has already been decrypted (which may be the case for TLS 1.3 where we don't know type until decryption) we queue the pending record to the rx_list. Next recvmsg() will pick it up from there. Queuing the skb to rx_list after zero-copy decrypt is not possible, since in that case we decrypted directly to the user space buffer, and we don't have an skb to queue (darg.skb points to the ciphertext skb for access to metadata like length). Only data records are allowed zero-copy, and we break the processing loop after each non-data record. So we should never zero-copy and then find out that the record type has changed. The corner case we missed is when the initial record comes from rx_list, and it's zero length.
02 / AFFECTED SOFTWARE
Affected packages
12 explicit affected versions
11 explicit affected versions
50 explicit affected versions
6 explicit affected versions
19 explicit affected versions
6 explicit affected versions
24 explicit affected versions
10 explicit affected versions
23 explicit affected versions
26 explicit affected versions
7 explicit affected versions
27 explicit affected versions
13 explicit affected versions
30 explicit affected versions
35 explicit affected versions
18 explicit affected versions
32 explicit affected versions
13 explicit affected versions
4 explicit affected versions
23 explicit affected versions
38 explicit affected versions
1 explicit affected versions
21 explicit affected versions
16 explicit affected versions
10 explicit affected versions
34 explicit affected versions
8 explicit affected versions
7 explicit affected versions
12 explicit affected versions
7 explicit affected versions
7 explicit affected versions
12 explicit affected versions
14 explicit affected versions
10 explicit affected versions
1 explicit affected versions
7 explicit affected versions
5 explicit affected versions
12 explicit affected versions
12 explicit affected versions
27 explicit affected versions
9 explicit affected versions
21 explicit affected versions
20 explicit affected versions
10 explicit affected versions
37 explicit affected versions
8 explicit affected versions
13 explicit affected versions
26 explicit affected versions
2 explicit affected versions
10 explicit affected versions
7 explicit affected versions
26 explicit affected versions
2 explicit affected versions
13 explicit affected versions
29 explicit affected versions
13 explicit affected versions
8 explicit affected versions
27 explicit affected versions
27 explicit affected versions
33 explicit affected versions
23 explicit affected versions
10 explicit affected versions
6 explicit affected versions
5 explicit affected versions
11 explicit affected versions
12 explicit affected versions
7 explicit affected versions
12 explicit affected versions
3 explicit affected versions
10 explicit affected versions
26 explicit affected versions
28 explicit affected versions
21 explicit affected versions
33 explicit affected versions
7 explicit affected versions
13 explicit affected versions
32 explicit affected versions
16 explicit affected versions
36 explicit affected versions
3 explicit affected versions
7 explicit affected versions
51 explicit affected versions
18 explicit affected versions
28 explicit affected versions
12 explicit affected versions
27 explicit affected versions
29 explicit affected versions
8 explicit affected versions
5 explicit affected versions
3 explicit affected versions
8 explicit affected versions
10 explicit affected versions
7 explicit affected versions
32 explicit affected versions
13 explicit affected versions
13 explicit affected versions
7 explicit affected versions
8 explicit affected versions
10 explicit affected versions
12 explicit affected versions
5 explicit affected versions
44 explicit affected versions
16 explicit affected versions
3 explicit affected versions
13 explicit affected versions
26 explicit affected versions
45 explicit affected versions
37 explicit affected versions
37 explicit affected versions
14 explicit affected versions
38 explicit affected versions
9 explicit affected versions
11 explicit affected versions
25 explicit affected versions
8 explicit affected versions
7 explicit affected versions
4 explicit affected versions
1 explicit affected versions
13 explicit affected versions
43 explicit affected versions
10 explicit affected versions
8 explicit affected versions
31 explicit affected versions
14 explicit affected versions
4 explicit affected versions
78 explicit affected versions
11 explicit affected versions
1 explicit affected versions
5 explicit affected versions
25 explicit affected versions
03 / CONNECTIONS
Connected vulnerabilities
04 / EVIDENCE
Source records
In the Linux kernel, the following vulnerability has been resolved: tls: fix handling of zero-length records on the rx_list Each recvmsg() call must process either - only contiguous DATA records (any number of them) - one non-DATA record If the next record has different type than what has already been processed we break out of the main processing loop. If the record has already been decrypted (which may be the case for TLS 1.3 where we don't know type until decryption) we queue the pending record to the rx_list. Next recvmsg() will pick it up from there. Queuing the skb to rx_list after zero-copy decrypt is not possible, since in that case we decrypted directly to the user space buffer, and we don't have an skb to queue (darg.skb points to the ciphertext skb for access to metadata like length). Only data records are allowed zero-copy, and we break the processing loop after each non-data record. So we should never zero-copy and then find out that the record type has changed. The corner case we missed is when the initial record comes from rx_list, and it's zero length.
05 / REFERENCES
Further evidence
- https://git.kernel.org/linus/62708b9452f8eb77513115b17c4f8d1a22ebf843
- https://git.kernel.org/stable/c/2902c3ebcca52ca845c03182000e8d71d3a5196f
- https://git.kernel.org/stable/c/29c0ce3c8cdb6dc5d61139c937f34cb888a6f42e
- https://git.kernel.org/stable/c/3439c15ae91a517cf3c650ea15a8987699416ad9
- https://git.kernel.org/stable/c/62708b9452f8eb77513115b17c4f8d1a22ebf843
- https://git.kernel.org/stable/c/c09dd3773b5950e9cfb6c9b9a5f6e36d06c62677
- https://ubuntu.com/security/CVE-2025-39682
- https://ubuntu.com/security/notices/USN-7833-1
- https://ubuntu.com/security/notices/USN-7833-2
- https://ubuntu.com/security/notices/USN-7833-3
- https://ubuntu.com/security/notices/USN-7833-4
- https://ubuntu.com/security/notices/USN-7834-1
- https://ubuntu.com/security/notices/USN-7835-1
- https://ubuntu.com/security/notices/USN-7835-2
- https://ubuntu.com/security/notices/USN-7835-3
- https://ubuntu.com/security/notices/USN-7835-4
- https://ubuntu.com/security/notices/USN-7835-5
- https://ubuntu.com/security/notices/USN-7835-6
- https://ubuntu.com/security/notices/USN-7856-1
- https://ubuntu.com/security/notices/USN-7887-1
- https://ubuntu.com/security/notices/USN-7887-2
- https://ubuntu.com/security/notices/USN-7940-1
- https://ubuntu.com/security/notices/USN-7940-2
- https://www.cve.org/CVERecord?id=CVE-2025-39682