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🛡️ CVE-2025-39946 — kernel

🔴 CVSS 9.8 — Critical ✅ No Known Exploit NVD
9.8
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

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

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 this vulnerability can be exploited

This issue can be reached over the network, attack complexity is low, an attacker needs no privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality high, integrity high, availability high.

CVSS metrics in full

The score comes from this vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

  • Attack vector: Network — reachable from anywhere that can route to the service.
  • Attack complexity: Low — the attack works reliably, with no preparation.
  • Privileges required: None — an unauthenticated stranger can try it.
  • User interaction: None — nobody has to be tricked into anything.
  • Scope: Unchanged — the damage stays inside the vulnerable component.
  • Confidentiality impact: High — total loss, or loss the attacker controls.
  • Integrity impact: High — total loss, or loss the attacker controls.
  • Availability impact: High — total loss, or loss the attacker controls.

Affected software

CVE-2025-39946 is recorded against 3 packages.

  • :linux-kernel: (from :0 up to :2026-03-05)
  • kernel (from 6.13.0 up to 6.16.9)
  • linux-kernel

Timeline and source

Published on 1 March 2026 and last revised on 20 August 2026. No public exploit is currently recorded for this entry. A vendor advisory or fix has been published. Record sourced from NVD.

References

source.android.com (Advisory)
android.googlesource.com (Fix)
android.googlesource.com (Fix)
android.googlesource.com (Fix)

Other advisories for this package

:linux-kernel: has other advisories on record. If you are patching this one, these are worth checking on the same host:

Details

Severity Critical
CVSS Score 9.8
CVSS Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CWE N/A
Public Exploit ✅ No
Source NVD
Published 2026-03-01
Updated 2026-08-20
Modified 2026-08-20

Affected Packages

Software From version Fixed in
:linux-kernel: :0 :2026-03-05
kernel 6.13.0 6.16.9
linux-kernel — —

Similar Threats

Exploit Protection

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CVE-2025-39946 carries CVSS 9.8 Critical rating. BotEraser checks your installation against this and other known CVE records, and blocks IPs associated with exploit activity.

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ⓘ Data Notice: The information presented above has been compiled from publicly available internet sources. Boteraser aggregates this data solely for informational purposes and does not independently classify, evaluate, or endorse any findings about the vulnerabilities listed. The accuracy and completeness of this information is the sole responsibility of the original publishers. Boteraser and its operators accept no liability for any decisions made based on this data.

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