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🛡️ CVE-2025-39682 — debian-linux

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

Description

tls: fix handling of zero-length records on the rx_list

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.

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-2025-39682 is recorded against 4 packages.

  • :linux-kernel: (from :0 up to :2026-03-05)
  • debian-linux
  • kernel (from 6.13.0 up to 6.16.4)
  • 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
debian-linux — —
kernel 6.13.0 6.16.4
linux-kernel — —

Similar Threats

Exploit Protection

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