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Fencer Vulns
high 7.8

CVE-2025-38616 json

tls: handle data disappearing from under the TLS ULP

published 2025-08-22 14 mo ago modified 2026-08-27 2 mo ago also EUVD-2025-26087

cvss
7.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 11%
public exploits
0
none known

Summary

In the Linux kernel, the following vulnerability has been resolved:

tls: handle data disappearing from under the TLS ULP

TLS expects that it owns the receive queue of the TCP socket. This cannot be guaranteed in case the reader of the TCP socket entered before the TLS ULP was installed, or uses some non-standard read API (eg. zerocopy ones). Replace the WARN_ON() and a buggy early exit (which leaves anchor pointing to a freed skb) with real error handling. Wipe the parsing state and tell the reader to retry.

We already reload the anchor every time we (re)acquire the socket lock, so the only condition we need to avoid is an out of bounds read (not having enough bytes in the socket for previously parsed record len).

If some data was read from under TLS but there's enough in the queue we'll reload and decrypt what is most likely not a valid TLS record. Leading to some undefined behavior from TLS perspective (corrupting a stream? missing an alert? missing an attack?) but no kernel crash should take place.

Patch / fix

  • Linux Linux 6.1.185, 6.6.103, 6.12.43, 6.15.11, 6.16.2, 6.17
  • linux Debian 12 6.1.187-1
  • linux Debian 13 6.12.43-1
  • linux Debian 14 6.16.3-1

debian advisories DEBIAN-CVE-2025-38616

  • linux Ubuntu 24.04 LTS 6.8.0-88.89
  • linux-aws Ubuntu 24.04 LTS 6.8.0-1043.45
  • linux-gcp Ubuntu 24.04 LTS 6.8.0-1044.47
  • linux-gke Ubuntu 24.04 LTS 6.8.0-1040.45
  • linux-ibm Ubuntu 24.04 LTS 6.8.0-1041.41
  • linux-azure Ubuntu 24.04 LTS 6.8.0-1044.50
  • linux-gkeop Ubuntu 24.04 LTS 6.8.0-1027.30
  • linux-raspi Ubuntu 24.04 LTS 6.8.0-1043.47

ubuntu advisories UBUNTU-CVE-2025-38616

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • kernel-livepatch-SLE16_Update_0 SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 5-160000.4.3
  • kernel-livepatch-SLE16-RT_Update_0 Linux Micro 6.2 4-160000.3.4
  • kernel-livepatch-MICRO-6-0-RT_Update_11 Linux Micro 6.1, Linux Micro 6.0 4-1.1
  • kernel-livepatch-MICRO-6-0-RT_Update_12 Linux Micro 6.1, Linux Micro 6.0 3-1.1
  • kernel-livepatch-MICRO-6-0-RT_Update_10 Linux Micro 6.1, Linux Micro 6.0 8-1.1
  • kernel-livepatch-MICRO-6-0_Update_12 Linux Micro 6.1, Linux Micro 6.0 3-1.1
  • kernel-livepatch-MICRO-6-0_Update_10 Linux Micro 6.1, Linux Micro 6.0 4-1.1
  • kernel-livepatch-MICRO-6-0_Update_11 Linux Micro 6.1, Linux Micro 6.0 3-1.1

suse advisories SUSE-SU-2026:20149-1SUSE-SU-2026:20169-1SUSE-SU-2026:20164-1SUSE-SU-2025:4311-1SUSE-SU-2025:4306-1SUSE-SU-2025:4302-1

  • kernel-rt openSUSE Leap 16.0 6.12.0-160000.6.1
  • dtb-aarch64 openSUSE Leap 16.0 6.12.0-160000.6.1
  • kernel-64kb openSUSE Leap 16.0 6.12.0-160000.6.1
  • kernel-syms openSUSE Leap 16.0 6.12.0-160000.6.1
  • kernel-obs-qa openSUSE Leap 16.0 6.12.0-160000.6.1
  • kernel-source openSUSE Leap 16.0 6.12.0-160000.6.1
  • kernel-default openSUSE Leap 16.0 6.12.0-160000.6.1
  • kernel-kvmsmall openSUSE Leap 16.0 6.12.0-160000.6.1

opensuse advisories openSUSE-SU-2025:20081-1

  • kernel Azure Linux 3.0 6.6.104.2-1

azure linux advisories AZL-66662

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2025-38616 updated cvss 4.1

kernel: Linux kernel: Denial of Service in kTLS due to race condition in receive path

  • Red Hat Enterprise Linux 9 rv, perf, rtla, kernel, bpftool, libperf, +83 more Red Hat Enterprise Linux 10 kernel
    affected: workaround, no fix available “Fix deferred”
  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more Red Hat Enterprise Linux 8 perf, kernel, bpftool, kernel-rt, kernel-core, kernel-tools, +29 more
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
4 mo ago

Exploit prediction

0.21% chance of exploitation in the next 30 days, higher than 11% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
NVD 3.1 7.1 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H

Affected products

  • Linux Linux

Classification

Weakness
Technology feeds

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.