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Fencer Vulns
critical 9.8

CVE-2025-38566 in the critical feed json

sunrpc: fix handling of server side tls alerts

published 2025-08-19 14 mo ago modified 2026-10-15 24 d ago also EUVD-2025-27905

cvss
9.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.6%
EPSS 0.6% chance of exploitation in 30 days, percentile 50%
public exploits
0
none known

Summary

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

sunrpc: fix handling of server side tls alerts

Scott Mayhew discovered a security exploit in NFS over TLS in tls_alert_recv() due to its assumption it can read data from the msg iterator's kvec..

kTLS implementation splits TLS non-data record payload between the control message buffer (which includes the type such as TLS aler or TLS cipher change) and the rest of the payload (say TLS alert's level/description) which goes into the msg payload buffer.

This patch proposes to rework how control messages are setup and used by sock_recvmsg().

If no control message structure is setup, kTLS layer will read and process TLS data record types. As soon as it encounters a TLS control message, it would return an error. At that point, NFS can setup a kvec backed msg buffer and read in the control message such as a TLS alert. Msg iterator can advance the kvec pointer as a part of the copy process thus we need to revert the iterator before calling into the tls_alert_recv.

Patch / fix

  • Linux Linux 6.6.102, 6.12.42, 6.15.10, 6.16.1, 6.17
  • linux Debian 13 6.12.43-1
  • linux Debian 14 6.16.3-1

debian advisories DEBIAN-CVE-2025-38566

  • linux Ubuntu 24.04 LTS 6.8.0-100.100
  • linux-aws Ubuntu 24.04 LTS 6.8.0-1046.49
  • linux-gcp Ubuntu 24.04 LTS 6.8.0-1047.50
  • linux-gke Ubuntu 24.04 LTS 6.8.0-1043.48
  • linux-ibm Ubuntu 24.04 LTS 6.8.0-1044.44
  • linux-azure Ubuntu 24.04 LTS 6.8.0-1046.52
  • linux-gkeop Ubuntu 24.04 LTS 6.8.0-1030.33
  • linux-raspi Ubuntu 24.04 LTS 6.8.0-1047.51

ubuntu advisories UBUNTU-CVE-2025-38566

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 RHEL 9 5.14.0-611.7.1.el9_7
  • rv RHEL 9 5.14.0-611.7.1.el9_7
  • perf RHEL 9 5.14.0-611.7.1.el9_7
  • rtla RHEL 9 5.14.0-611.7.1.el9_7
  • libperf RHEL 9 5.14.0-611.7.1.el9_7
  • kernel-rt RHEL 9 5.14.0-611.7.1.el9_7
  • kernel-64k RHEL 9 5.14.0-611.7.1.el9_7
  • kernel-core RHEL 9 5.14.0-611.7.1.el9_7

red hat advisories RHSA-2025:21112RHSA-2025:18281RHSA-2025:17958RHSA-2025:16354

  • kernel-rt Linux Micro 6.2 6.12.0-160000.6.1
  • kernel-64kb SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 6.12.0-160000.6.1
  • kernel-source SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 6.12.0-160000.6.1
  • kernel-default SLES 16.0, SLE High Availability Extension 16.0, Linux Micro 6.2 +1 more 6.12.0-160000.6.1
  • kernel-default-base SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 6.12.0-160000.6.1.160000.2.4
  • kernel-syms SLES 16.0, Linux Micro Extras 6.2, SLES for SAP applications 16.0 6.12.0-160000.6.1
  • kernel-obs-qa SLES for SAP applications 16.0, SLES 16.0 6.12.0-160000.6.1
  • kernel-kvmsmall SLES for SAP applications 16.0, SLES 16.0 6.12.0-160000.6.1

suse advisories SUSE-SU-2025:21074-1SUSE-SU-2025:21139-1SUSE-SU-2026:20560-1SUSE-SU-2025:21179-1SUSE-SU-2025:20891-1SUSE-SU-2025:20890-1

  • 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 AlmaLinux 9 5.14.0-570.55.1.el9_6
  • rv AlmaLinux 9 5.14.0-570.55.1.el9_6
  • perf AlmaLinux 9 5.14.0-570.55.1.el9_6
  • rtla AlmaLinux 9 5.14.0-570.55.1.el9_6
  • libperf AlmaLinux 9 5.14.0-570.55.1.el9_6
  • kernel-rt AlmaLinux 9 5.14.0-570.55.1.el9_6
  • kernel-64k AlmaLinux 9 5.14.0-570.55.1.el9_6
  • kernel-core AlmaLinux 9 5.14.0-570.55.1.el9_6

almalinux advisories ALSA-2025:18281ALSA-2025:16354

  • kernel Rocky Linux 10 6.12.0-55.34.1.el10_0

rocky linux advisories RLSA-2025:16354

  • kernel Azure Linux 3.0 6.6.104.2-1

azure linux advisories AZL-66485

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-2025-38566 updated cvss 7.5

kernel: sunrpc: fix handling of server side tls alerts

  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more
    affected: workaround, no fix planned “To mitigate this issue, prevent module sunrpc from being loaded. Please see https://access.redhat.com/solutions/41278 for how to blacklist a kernel module to prevent it from loading automatically.”
  • Red Hat Enterprise Linux 9 kernel-rt, kernel-rt-kvm, kernel-rt-core, kernel-rt-modules, kernel-rt-debug-kvm, kernel-rt-debug-core, +12 more
    affected: workaround, no fix available “To mitigate this issue, prevent module sunrpc from being loaded. Please see https://access.redhat.com/solutions/41278 for how to blacklist a kernel module to prevent it from loading automatically.”
  • Red Hat CodeReady Linux Builder EUS (v.9.4) libperf 5.14.0-427.94.1.el9_4, kernel-debuginfo-common-s390x 5.14.0-427.94.1.el9_4, kernel-debuginfo-common-x86_64 5.14.0-427.94.1.el9_4, kernel-debuginfo-common-aarch64 5.14.0-427.94.1.el9_4, kernel-debuginfo-common-ppc64le 5.14.0-427.94.1.el9_4
    fixed: vendor fix “To mitigate this issue, prevent module sunrpc from being loaded. Please see https://access.redhat.com/solutions/41278 for how to blacklist a kernel module to prevent it from loading automatically.” RHSA-2025:17958
  • Red Hat Enterprise Linux AppStream (v. 9) rv 5.14.0-611.7.1.el9_7, rv 5.14.0-570.55.1.el9_6, perf 5.14.0-611.7.1.el9_7, rtla 5.14.0-611.7.1.el9_7, perf 5.14.0-570.55.1.el9_6, rtla 5.14.0-570.55.1.el9_6, +20 more
    fixed: vendor fix “To mitigate this issue, prevent module sunrpc from being loaded. Please see https://access.redhat.com/solutions/41278 for how to blacklist a kernel module to prevent it from loading automatically.” RHSA-2025:18281
  • Red Hat Enterprise Linux AppStream (v. 10) rv 6.12.0-55.34.1.el10_0, perf 6.12.0-55.34.1.el10_0, rtla 6.12.0-55.34.1.el10_0, python3-perf 6.12.0-55.34.1.el10_0, kernel-devel-matched 6.12.0-55.34.1.el10_0, kernel-64k-devel-matched 6.12.0-55.34.1.el10_0, +7 more
    fixed: vendor fix “To mitigate this issue, prevent module sunrpc from being loaded. Please see https://access.redhat.com/solutions/41278 for how to blacklist a kernel module to prevent it from loading automatically.” RHSA-2025:16354
  • Red Hat Enterprise Linux AppStream EUS (v.9.4) rv 5.14.0-427.94.1.el9_4, perf 5.14.0-427.94.1.el9_4, rtla 5.14.0-427.94.1.el9_4, kernel-devel-matched 5.14.0-427.94.1.el9_4, kernel-64k-devel-matched 5.14.0-427.94.1.el9_4, kernel-debug-devel-matched 5.14.0-427.94.1.el9_4, +6 more
    fixed: vendor fix “To mitigate this issue, prevent module sunrpc from being loaded. Please see https://access.redhat.com/solutions/41278 for how to blacklist a kernel module to prevent it from loading automatically.” RHSA-2025:17958
  • Red Hat Enterprise Linux BaseOS (v. 9) kernel 5.14.0-611.7.1.el9_7, kernel 5.14.0-570.55.1.el9_6, kernel-64k 5.14.0-611.7.1.el9_7, kernel-64k 5.14.0-570.55.1.el9_6, kernel-core 5.14.0-611.7.1.el9_7, kernel-core 5.14.0-570.55.1.el9_6, +60 more
    fixed: vendor fix “To mitigate this issue, prevent module sunrpc from being loaded. Please see https://access.redhat.com/solutions/41278 for how to blacklist a kernel module to prevent it from loading automatically.” RHSA-2025:18281
  • Red Hat Enterprise Linux BaseOS (v. 10) kernel 6.12.0-55.34.1.el10_0, kernel-64k 6.12.0-55.34.1.el10_0, kernel-core 6.12.0-55.34.1.el10_0, kernel-tools 6.12.0-55.34.1.el10_0, kernel-modules 6.12.0-55.34.1.el10_0, kernel-64k-core 6.12.0-55.34.1.el10_0, +27 more
    fixed: vendor fix “To mitigate this issue, prevent module sunrpc from being loaded. Please see https://access.redhat.com/solutions/41278 for how to blacklist a kernel module to prevent it from loading automatically.” RHSA-2025:16354
show 10 more
  • Red Hat Enterprise Linux BaseOS EUS (v.9.4) bpftool 7.3.0-427.94.1.el9_4, kernel 5.14.0-427.94.1.el9_4, kernel-64k 5.14.0-427.94.1.el9_4, kernel-core 5.14.0-427.94.1.el9_4, kernel-tools 5.14.0-427.94.1.el9_4, python3-perf 5.14.0-427.94.1.el9_4, +28 more
    fixed: vendor fix “To mitigate this issue, prevent module sunrpc from being loaded. Please see https://access.redhat.com/solutions/41278 for how to blacklist a kernel module to prevent it from loading automatically.” RHSA-2025:17958
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 9) libperf 5.14.0-611.7.1.el9_7, libperf 5.14.0-570.55.1.el9_6, kernel-debuginfo-common-s390x 5.14.0-611.7.1.el9_7, kernel-debuginfo-common-s390x 5.14.0-570.55.1.el9_6, kernel-debuginfo-common-x86_64 5.14.0-611.7.1.el9_7, kernel-debuginfo-common-aarch64 5.14.0-611.7.1.el9_7, +4 more
    fixed: vendor fix “To mitigate this issue, prevent module sunrpc from being loaded. Please see https://access.redhat.com/solutions/41278 for how to blacklist a kernel module to prevent it from loading automatically.” RHSA-2025:18281
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) libperf 6.12.0-55.34.1.el10_0, kernel-debuginfo-common-s390x 6.12.0-55.34.1.el10_0, kernel-debuginfo-common-x86_64 6.12.0-55.34.1.el10_0, kernel-debuginfo-common-aarch64 6.12.0-55.34.1.el10_0, kernel-debuginfo-common-ppc64le 6.12.0-55.34.1.el10_0
    fixed: vendor fix “To mitigate this issue, prevent module sunrpc from being loaded. Please see https://access.redhat.com/solutions/41278 for how to blacklist a kernel module to prevent it from loading automatically.” RHSA-2025:16354
  • Red Hat Enterprise Linux Real Time (v. 9) kernel-rt 5.14.0-611.7.1.el9_7, kernel-rt 5.14.0-570.55.1.el9_6, kernel-rt-64k 5.14.0-611.7.1.el9_7, kernel-rt-64k 5.14.0-570.55.1.el9_6, kernel-rt-core 5.14.0-611.7.1.el9_7, kernel-rt-core 5.14.0-570.55.1.el9_6, +34 more
    fixed: vendor fix “To mitigate this issue, prevent module sunrpc from being loaded. Please see https://access.redhat.com/solutions/41278 for how to blacklist a kernel module to prevent it from loading automatically.” RHSA-2025:18281
  • Red Hat Enterprise Linux Real Time (v. 10) kernel-rt 6.12.0-55.34.1.el10_0, kernel-rt-64k 6.12.0-55.34.1.el10_0, kernel-rt-core 6.12.0-55.34.1.el10_0, kernel-rt-modules 6.12.0-55.34.1.el10_0, kernel-rt-64k-core 6.12.0-55.34.1.el10_0, kernel-rt-debug-core 6.12.0-55.34.1.el10_0, +14 more
    fixed: vendor fix “To mitigate this issue, prevent module sunrpc from being loaded. Please see https://access.redhat.com/solutions/41278 for how to blacklist a kernel module to prevent it from loading automatically.” RHSA-2025:16354
  • Red Hat Enterprise Linux Real Time EUS (v.9.4) kernel-rt 5.14.0-427.94.1.el9_4, kernel-rt-core 5.14.0-427.94.1.el9_4, kernel-rt-modules 5.14.0-427.94.1.el9_4, kernel-rt-debug-core 5.14.0-427.94.1.el9_4, kernel-rt-modules-core 5.14.0-427.94.1.el9_4, kernel-rt-debug-modules 5.14.0-427.94.1.el9_4, +4 more
    fixed: vendor fix “To mitigate this issue, prevent module sunrpc from being loaded. Please see https://access.redhat.com/solutions/41278 for how to blacklist a kernel module to prevent it from loading automatically.” RHSA-2025:17958
  • Red Hat Enterprise Linux Real Time for NFV (v. 9) kernel-rt 5.14.0-611.7.1.el9_7, kernel-rt 5.14.0-570.55.1.el9_6, kernel-rt-core 5.14.0-611.7.1.el9_7, kernel-rt-kvm 5.14.0-570.55.1.el9_6, kernel-rt-core 5.14.0-570.55.1.el9_6, kernel-rt-modules 5.14.0-611.7.1.el9_7, +16 more
    fixed: vendor fix “To mitigate this issue, prevent module sunrpc from being loaded. Please see https://access.redhat.com/solutions/41278 for how to blacklist a kernel module to prevent it from loading automatically.” RHSA-2025:18281
  • Red Hat Enterprise Linux Real Time for NFV (v. 10) kernel-rt 6.12.0-55.34.1.el10_0, kernel-rt-kvm 6.12.0-55.34.1.el10_0, kernel-rt-core 6.12.0-55.34.1.el10_0, kernel-rt-modules 6.12.0-55.34.1.el10_0, kernel-rt-debug-kvm 6.12.0-55.34.1.el10_0, kernel-rt-debug-core 6.12.0-55.34.1.el10_0, +6 more
    fixed: vendor fix “To mitigate this issue, prevent module sunrpc from being loaded. Please see https://access.redhat.com/solutions/41278 for how to blacklist a kernel module to prevent it from loading automatically.” RHSA-2025:16354
  • Red Hat Enterprise Linux Real Time for NFV EUS (v.9.4) kernel-rt 5.14.0-427.94.1.el9_4, kernel-rt-kvm 5.14.0-427.94.1.el9_4, kernel-rt-core 5.14.0-427.94.1.el9_4, kernel-rt-modules 5.14.0-427.94.1.el9_4, kernel-rt-debug-kvm 5.14.0-427.94.1.el9_4, kernel-rt-debug-core 5.14.0-427.94.1.el9_4, +6 more
    fixed: vendor fix “To mitigate this issue, prevent module sunrpc from being loaded. Please see https://access.redhat.com/solutions/41278 for how to blacklist a kernel module to prevent it from loading automatically.” RHSA-2025:17958
  • 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
yes
Technical impact
total
Assessed
24 d ago

Exploit prediction

0.63% chance of exploitation in the next 30 days, higher than 50% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected products

  • Linux Linux

Classification

Weakness
  • CWE-754 Improper Check for Unusual or Exceptional Conditions
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.