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Fencer Vulns
high 7.8

CVE-2026-23066 json

rxrpc: Fix recvmsg() unconditional requeue

published 2026-02-04 9 mo ago modified 2026-10-19 20 d ago also EUVD-2026-5478

cvss
7.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.1%
EPSS 0.1% chance of exploitation in 30 days, percentile 1%
public exploits
0
none known

Summary

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

rxrpc: Fix recvmsg() unconditional requeue

If rxrpc_recvmsg() fails because MSG_DONTWAIT was specified but the call at the front of the recvmsg queue already has its mutex locked, it requeues the call - whether or not the call is already queued. The call may be on the queue because MSG_PEEK was also passed and so the call was not dequeued or because the I/O thread requeued it.

The unconditional requeue may then corrupt the recvmsg queue, leading to things like UAFs or refcount underruns.

Fix this by only requeuing the call if it isn't already on the queue - and moving it to the front if it is already queued. If we don't queue it, we have to put the ref we obtained by dequeuing it.

Also, MSG_PEEK doesn't dequeue the call so shouldn't call rxrpc_notify_socket() for the call if we didn't use up all the data on the queue, so fix that also.

Patch / fix

  • Linux Linux 5.10.258, 5.15.209, 6.1.175, 6.6.130, 6.12.78, 6.18.8, 6.19
  • linux Debian 12 6.1.176-1
  • linux Debian 13 6.12.85-1
  • linux Debian 14 6.18.8-1

debian advisories DEBIAN-CVE-2026-23066

  • linux Ubuntu 22.04 LTS 5.15.0-186.196
  • linux Ubuntu 24.04 LTS 6.8.0-136.136
  • linux-aws Ubuntu 22.04 LTS 5.15.0-1112.119
  • linux-aws Ubuntu 24.04 LTS 6.8.0-1061.64
  • linux-gcp Ubuntu 22.04 LTS 5.15.0-1112.122
  • linux-gcp Ubuntu 24.04 LTS 6.8.0-1064.72
  • linux-gke Ubuntu 22.04 LTS 5.15.0-1108.114
  • linux-gke Ubuntu 24.04 LTS 6.8.0-1059.67

ubuntu advisories UBUNTU-CVE-2026-23066

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 9.4 EUS 5.14.0-427.121.1.el9_4
  • rv RHEL 9.4 EUS 5.14.0-427.121.1.el9_4
  • perf RHEL 9.4 EUS 5.14.0-427.121.1.el9_4
  • rtla RHEL 9.4 EUS 5.14.0-427.121.1.el9_4
  • bpftool RHEL 9.4 EUS 7.3.0-427.121.1.el9_4
  • libperf RHEL 9.4 EUS 5.14.0-427.121.1.el9_4
  • kernel-rt RHEL 9.4 EUS 5.14.0-427.121.1.el9_4
  • kernel-64k RHEL 9.4 EUS 5.14.0-427.121.1.el9_4

red hat advisories RHSA-2026:10108RHSA-2026:9644RHSA-2026:9512RHSA-2026:9112RHSA-2026:9095

  • kernel-syms SLES 16.0, Linux Micro Extras 6.2, SLES for SAP applications 16.0 6.12.0-160000.27.1
  • kernel-obs-build Linux Micro Extras 6.2 6.12.0-160000.27.1
  • kernel-rt Linux Micro 6.2 6.12.0-160000.27.1
  • kernel-64kb SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 6.12.0-160000.27.1
  • kernel-source SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 6.12.0-160000.27.1
  • kernel-default SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 6.12.0-160000.27.1
  • kernel-default-base SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 6.12.0-160000.27.1.160000.2.8
  • kernel-azure SLES for SAP applications 16.0, SLES 16.0 6.12.0-160000.27.1

suse advisories SUSE-SU-2026:20873-1SUSE-SU-2026:20838-1SUSE-SU-2026:20931-1

  • kernel-rt openSUSE Leap 16.0 6.12.0-160000.27.1
  • dtb-aarch64 openSUSE Leap 16.0 6.12.0-160000.27.1
  • kernel-64kb openSUSE Leap 16.0 6.12.0-160000.27.1
  • kernel-syms openSUSE Leap 16.0 6.12.0-160000.27.1
  • kernel-azure openSUSE Leap 16.0 6.12.0-160000.27.1
  • kernel-obs-qa openSUSE Leap 16.0 6.12.0-160000.27.1
  • kernel-source openSUSE Leap 16.0 6.12.0-160000.27.1
  • kernel-default openSUSE Leap 16.0 6.12.0-160000.27.1

opensuse advisories openSUSE-SU-2026:20416-1

  • kernel Azure Linux 3.0 6.6.130.1-3

azure linux advisories AZL-77250

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-2026-23066 updated cvss 7.4

kernel: Linux kernel: Denial of Service via unsafe requeue in rxrpc_recvmsg

  • Red Hat Enterprise Linux 9 rv, perf, rtla, kernel, bpftool, libperf, +83 more Red Hat Enterprise Linux 10 kernel
    affected: workaround, no fix available “To mitigate this issue, prevent module rxrpc 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 5.14.0-427.121.1.el9_4, kernel-debuginfo-common-s390x 5.14.0-427.121.1.el9_4, kernel-debuginfo-common-x86_64 5.14.0-427.121.1.el9_4, kernel-debuginfo-common-aarch64 5.14.0-427.121.1.el9_4, kernel-debuginfo-common-ppc64le 5.14.0-427.121.1.el9_4
    fixed: vendor fix “To mitigate this issue, prevent module rxrpc 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-2026:10108
  • Red Hat CodeReady Linux Builder EUS (v.9.6) libperf 5.14.0-570.108.1.el9_6, kernel-debuginfo-common-s390x 5.14.0-570.108.1.el9_6, kernel-debuginfo-common-x86_64 5.14.0-570.108.1.el9_6, kernel-debuginfo-common-aarch64 5.14.0-570.108.1.el9_6, kernel-debuginfo-common-ppc64le 5.14.0-570.108.1.el9_6
    fixed: vendor fix “To mitigate this issue, prevent module rxrpc 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-2026:9112
  • Red Hat Enterprise Linux AppStream E4S (v.9.2) perf 5.14.0-284.166.1.el9_2, rtla 5.14.0-284.166.1.el9_2, kernel-devel-matched 5.14.0-284.166.1.el9_2, kernel-64k-devel-matched 5.14.0-284.166.1.el9_2, kernel-debug-devel-matched 5.14.0-284.166.1.el9_2, kernel-debuginfo-common-s390x 5.14.0-284.166.1.el9_2, +5 more
    fixed: vendor fix “To mitigate this issue, prevent module rxrpc 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-2026:9644
  • Red Hat Enterprise Linux AppStream EUS (v. 10.0) rv 6.12.0-55.69.1.el10_0, perf 6.12.0-55.69.1.el10_0, rtla 6.12.0-55.69.1.el10_0, python3-perf 6.12.0-55.69.1.el10_0, kernel-devel-matched 6.12.0-55.69.1.el10_0, kernel-64k-devel-matched 6.12.0-55.69.1.el10_0, +7 more
    fixed: vendor fix “To mitigate this issue, prevent module rxrpc 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-2026:9095
  • Red Hat Enterprise Linux AppStream EUS (v.9.4) rv 5.14.0-427.121.1.el9_4, perf 5.14.0-427.121.1.el9_4, rtla 5.14.0-427.121.1.el9_4, kernel-devel-matched 5.14.0-427.121.1.el9_4, kernel-64k-devel-matched 5.14.0-427.121.1.el9_4, kernel-debug-devel-matched 5.14.0-427.121.1.el9_4, +6 more
    fixed: vendor fix “To mitigate this issue, prevent module rxrpc 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-2026:10108
  • Red Hat Enterprise Linux AppStream EUS (v.9.6) rv 5.14.0-570.108.1.el9_6, perf 5.14.0-570.108.1.el9_6, rtla 5.14.0-570.108.1.el9_6, python3-perf 5.14.0-570.108.1.el9_6, kernel-devel-matched 5.14.0-570.108.1.el9_6, kernel-64k-devel-matched 5.14.0-570.108.1.el9_6, +7 more
    fixed: vendor fix “To mitigate this issue, prevent module rxrpc 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-2026:9112
  • Red Hat Enterprise Linux BaseOS E4S (v.9.2) bpftool 7.0.0-284.166.1.el9_2, kernel 5.14.0-284.166.1.el9_2, kernel-64k 5.14.0-284.166.1.el9_2, kernel-core 5.14.0-284.166.1.el9_2, kernel-tools 5.14.0-284.166.1.el9_2, python3-perf 5.14.0-284.166.1.el9_2, +28 more
    fixed: vendor fix “To mitigate this issue, prevent module rxrpc 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-2026:9644
show 13 more
  • Red Hat Enterprise Linux BaseOS EUS (v. 10.0) kernel 6.12.0-55.69.1.el10_0, kernel-64k 6.12.0-55.69.1.el10_0, kernel-core 6.12.0-55.69.1.el10_0, kernel-tools 6.12.0-55.69.1.el10_0, kernel-modules 6.12.0-55.69.1.el10_0, kernel-64k-core 6.12.0-55.69.1.el10_0, +27 more
    fixed: vendor fix “To mitigate this issue, prevent module rxrpc 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-2026:9095
  • Red Hat Enterprise Linux BaseOS EUS (v.9.4) bpftool 7.3.0-427.121.1.el9_4, kernel 5.14.0-427.121.1.el9_4, kernel-64k 5.14.0-427.121.1.el9_4, kernel-core 5.14.0-427.121.1.el9_4, kernel-tools 5.14.0-427.121.1.el9_4, python3-perf 5.14.0-427.121.1.el9_4, +28 more
    fixed: vendor fix “To mitigate this issue, prevent module rxrpc 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-2026:10108
  • Red Hat Enterprise Linux BaseOS EUS (v.9.6) kernel 5.14.0-570.108.1.el9_6, kernel-64k 5.14.0-570.108.1.el9_6, kernel-core 5.14.0-570.108.1.el9_6, kernel-tools 5.14.0-570.108.1.el9_6, kernel-modules 5.14.0-570.108.1.el9_6, kernel-64k-core 5.14.0-570.108.1.el9_6, +27 more
    fixed: vendor fix “To mitigate this issue, prevent module rxrpc 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-2026:9112
  • Red Hat Enterprise Linux CodeReady Linux Builder EUS (v. 10.0) libperf 6.12.0-55.69.1.el10_0, kernel-debuginfo-common-s390x 6.12.0-55.69.1.el10_0, kernel-debuginfo-common-x86_64 6.12.0-55.69.1.el10_0, kernel-debuginfo-common-aarch64 6.12.0-55.69.1.el10_0, kernel-debuginfo-common-ppc64le 6.12.0-55.69.1.el10_0
    fixed: vendor fix “To mitigate this issue, prevent module rxrpc 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-2026:9095
  • Red Hat Enterprise Linux Real Time E4S (v.9.2) kernel-rt 5.14.0-284.166.1.rt14.451.el9_2, kernel-rt-core 5.14.0-284.166.1.rt14.451.el9_2, kernel-rt-modules 5.14.0-284.166.1.rt14.451.el9_2, kernel-rt-debug-core 5.14.0-284.166.1.rt14.451.el9_2, kernel-rt-modules-core 5.14.0-284.166.1.rt14.451.el9_2, kernel-rt-debug-modules 5.14.0-284.166.1.rt14.451.el9_2, +4 more
    fixed: vendor fix “To mitigate this issue, prevent module rxrpc 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-2026:9512
  • Red Hat Enterprise Linux Real Time EUS (v. 10.0) kernel-rt 6.12.0-55.69.1.el10_0, kernel-rt-64k 6.12.0-55.69.1.el10_0, kernel-rt-core 6.12.0-55.69.1.el10_0, kernel-rt-modules 6.12.0-55.69.1.el10_0, kernel-rt-64k-core 6.12.0-55.69.1.el10_0, kernel-rt-debug-core 6.12.0-55.69.1.el10_0, +14 more
    fixed: vendor fix “To mitigate this issue, prevent module rxrpc 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-2026:9095
  • Red Hat Enterprise Linux Real Time EUS (v.9.4) kernel-rt 5.14.0-427.121.1.el9_4, kernel-rt-core 5.14.0-427.121.1.el9_4, kernel-rt-modules 5.14.0-427.121.1.el9_4, kernel-rt-debug-core 5.14.0-427.121.1.el9_4, kernel-rt-modules-core 5.14.0-427.121.1.el9_4, kernel-rt-debug-modules 5.14.0-427.121.1.el9_4, +4 more
    fixed: vendor fix “To mitigate this issue, prevent module rxrpc 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-2026:10108
  • Red Hat Enterprise Linux Real Time EUS (v.9.6) kernel-rt 5.14.0-570.108.1.el9_6, kernel-rt-64k 5.14.0-570.108.1.el9_6, kernel-rt-core 5.14.0-570.108.1.el9_6, kernel-rt-modules 5.14.0-570.108.1.el9_6, kernel-rt-64k-core 5.14.0-570.108.1.el9_6, kernel-rt-debug-core 5.14.0-570.108.1.el9_6, +14 more
    fixed: vendor fix “To mitigate this issue, prevent module rxrpc 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-2026:9112
  • Red Hat Enterprise Linux Real Time for NFV E4S (v.9.2) kernel-rt 5.14.0-284.166.1.rt14.451.el9_2, kernel-rt-kvm 5.14.0-284.166.1.rt14.451.el9_2, kernel-rt-core 5.14.0-284.166.1.rt14.451.el9_2, kernel-rt-modules 5.14.0-284.166.1.rt14.451.el9_2, kernel-rt-debug-kvm 5.14.0-284.166.1.rt14.451.el9_2, kernel-rt-debug-core 5.14.0-284.166.1.rt14.451.el9_2, +6 more
    fixed: vendor fix “To mitigate this issue, prevent module rxrpc 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-2026:9512
  • Red Hat Enterprise Linux Real Time for NFV EUS (v. 10.0) kernel-rt 6.12.0-55.69.1.el10_0, kernel-rt-kvm 6.12.0-55.69.1.el10_0, kernel-rt-core 6.12.0-55.69.1.el10_0, kernel-rt-modules 6.12.0-55.69.1.el10_0, kernel-rt-debug-kvm 6.12.0-55.69.1.el10_0, kernel-rt-debug-core 6.12.0-55.69.1.el10_0, +6 more
    fixed: vendor fix “To mitigate this issue, prevent module rxrpc 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-2026:9095
  • Red Hat Enterprise Linux Real Time for NFV EUS (v.9.4) kernel-rt 5.14.0-427.121.1.el9_4, kernel-rt-kvm 5.14.0-427.121.1.el9_4, kernel-rt-core 5.14.0-427.121.1.el9_4, kernel-rt-modules 5.14.0-427.121.1.el9_4, kernel-rt-debug-kvm 5.14.0-427.121.1.el9_4, kernel-rt-debug-core 5.14.0-427.121.1.el9_4, +6 more
    fixed: vendor fix “To mitigate this issue, prevent module rxrpc 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-2026:10108
  • Red Hat Enterprise Linux Real Time for NFV EUS (v.9.6) kernel-rt 5.14.0-570.108.1.el9_6, kernel-rt-kvm 5.14.0-570.108.1.el9_6, kernel-rt-core 5.14.0-570.108.1.el9_6, kernel-rt-modules 5.14.0-570.108.1.el9_6, kernel-rt-debug-kvm 5.14.0-570.108.1.el9_6, kernel-rt-debug-core 5.14.0-570.108.1.el9_6, +6 more
    fixed: vendor fix “To mitigate this issue, prevent module rxrpc 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-2026:9112
  • 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, +18 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 ICSA-26-295-16 updated cvss 7.8

Siemens SIMATIC S7-1500 TM MFP

  • Siemens SIMATIC S7-1500 TM MFP - GNU/Linux subsystem
    affected: mitigation, no fix available

Facts from CISA's republication of the vendor's own advisory (CSAF); the linked advisory is the authoritative source. CISA notification · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
total
Assessed
24 d ago

Exploit prediction

0.12% chance of exploitation in the next 30 days, higher than 1% 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 5.5 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Affected products

  • Linux Linux
  • Siemens SIMATIC S7-1500 TM MFP - GNU/Linux subsystem

Classification

Weakness
  • CWE-362 Concurrent Execution using Shared Resource with Improper Synchronization
  • CWE-674 Uncontrolled Recursion
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.