CVE-2025-39946

tls: make sure to abort the stream if headers are bogus

MEDIUM
5.5
CVSS Score
Published: October 4, 2025 at 07:31 AM UTC
Updated: October 19, 2026 at 09:10 PM UTC
1 product affected across 1 vendorLinux Kernel

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Severity
MEDIUM5.5
Exploit prediction
EPSS 10%
SSVC
No known exploit

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

6.0 ≤ v < 6.1.1546.13 ≤ v < 6.16.96.2 ≤ v < 6.6.1086.7 ≤ v < 6.12.496.06.176.17 rc16.17 rc26.17 rc36.17 rc46.17 rc56.17 rc684c61fe1a75b4255df1e1e7c054c9e6d048da417
Vendor states this is fixed in 0aeb54ac4cd5cf8f60131b4d9ec0b6dc9c27b20d (fixed)
Vendor states this is fixed in 208640e6225cc929a05adbf79d1df558add3e231 (fixed)
Vendor states this is fixed in 4cefe5be73886f383639fe0850bb72d5b568a7b9 (fixed)
Vendor states this is fixed in 61ca2da5fb8f433ce8bbd1657c84a86272133e6b (fixed)
Vendor states this is fixed in b36462146d86b1f22e594fe4dae611dffacfb203 (fixed)
Vendor states this is fixed in 6.0 (unaffected)
Vendor states this is fixed in 6.1.154 (unaffected)
Vendor states this is fixed in 6.12.49 (unaffected)
Vendor states this is fixed in 6.16.9 (unaffected)
Vendor states this is fixed in 6.17 (unaffected)
Vendor states this is fixed in 6.6.108 (unaffected)

SSVC — Action Prioritization

SSVCNo known exploitAutomatableTotal impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

Attack Vector
LOCAL
Complexity
LOW
Privileges
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Vector?

Quick Info

StatusANALYZED
CWE
NVD-CWE-noinfo

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