CVE-2025-39946

CVE-2025-39946

Critical · published October 4, 2025

CVSS v3.1
9.8
EPSS
10%
Percentile
95.5
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v3.1
9.8 · CRITICAL
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CVSS v4.0
Not supplied
EPSS
0.09567 · 95.5th percentile
Published
2025-10-04T12:15Z
Affected products (10)
ProductVersionsFixed in
linux/linux_kernel≥ 6.0, < 6.1.1546.1.154
linux/linux_kernel≥ 6.2, < 6.6.1086.6.108
linux/linux_kernel≥ 6.7, < 6.12.496.12.49
linux/linux_kernel≥ 6.13, < 6.16.96.16.9
linux/linux_kernelall versions—
linux/linux_kernelall versions—
linux/linux_kernelall versions—
linux/linux_kernelall versions—
linux/linux_kernelall versions—
linux/linux_kernelall versions—
References (5)
EPSS history
Timeline
  • 04 OCT 07:31Z
    tls: make sure to abort the stream if headers are bogus
    cvelistv5