CVE-2025-39946
Description
In the Linux kernel, the following vulnerability has been resolved: tls: make sure to abort the stream if headers are bogus Normally we wait for the socket to buffer up the whole record before we service it. If the socket has a tiny buffer, however, we read out the data sooner, to prevent connection stalls. Make sure that we abort the connection when we find out late that the record is actually invalid. Retrying the parsing is fine in itself but since we copy some more data each time before we parse we can overflow the allocated skb space. Constructing a scenario in which we're under pressure without enough data in the socket to parse the length upfront is quite hard. syzbot figured out a way to do this by serving us the header in small OOB sends, and then filling in the recvbuf with a large normal send. Make sure that tls_rx_msg_size() aborts strp, if we reach an invalid record there's really no way to recover.
How to fix CVE-2025-39946
To remediate CVE-2025-39946, upgrade the affected package to a fixed version below.
- —upgrade to 6.1.158-1 or later
- —upgrade to 6.1.158-1~deb11u1 or later
Is CVE-2025-39946 being exploited?
Moderate — EPSS is 8.9%. Track this CVE but it's not at the top of the prioritisation list.
Affected packages (2)
- from 0, < 6.1.158-1
- from 0, < 6.1.158-1~deb11u1
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 3.1 | MEDIUM5.5 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H |