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Fencer Vulns
high 7.8

CVE-2024-26923 json

af_unix: Fix garbage collector racing against connect()

published 2024-04-24 2 y ago modified 2026-11-03 5 d ago also EUVD-2024-24185

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 10%
public exploits
0
none known

Summary

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

af_unix: Fix garbage collector racing against connect()

Garbage collector does not take into account the risk of embryo getting enqueued during the garbage collection. If such embryo has a peer that carries SCM_RIGHTS, two consecutive passes of scan_children() may see a different set of children. Leading to an incorrectly elevated inflight count, and then a dangling pointer within the gc_inflight_list.

sockets are AF_UNIX/SOCK_STREAM S is an unconnected socket L is a listening in-flight socket bound to addr, not in fdtable V's fd will be passed via sendmsg(), gets inflight count bumped

connect(S, addr) sendmsg(S, [V]); close(V) __unix_gc() ---------------- ------------------------- -----------

NS = unix_create1() skb1 = sock_wmalloc(NS) L = unix_find_other(addr) unix_state_lock(L) unix_peer(S) = NS // V count=1 inflight=0

NS = unix_peer(S) skb2 = sock_alloc() skb_queue_tail(NS, skb2[V])

// V became in-flight // V count=2 inflight=1

close(V)

// V count=1 inflight=1 // GC candidate condition met

for u in gc_inflight_list: if (total_refs == inflight_refs) add u to gc_candidates

// gc_candidates={L, V}

for u in gc_candidates: scan_children(u, dec_inflight)

// embryo (skb1) was not // reachable from L yet, so V's // inflight remains unchanged __skb_queue_tail(L, skb1) unix_state_unlock(L) for u in gc_candidates: if (u.inflight) scan_children(u, inc_inflight_move_tail)

// V count=1 inflight=2 (!)

If there is a GC-candidate listening socket, lock/unlock its state. This makes GC wait until the end of any ongoing connect() to that socket. After flipping the lock, a possibly SCM-laden embryo is already enqueued. And if there is another embryo coming, it can not possibly carry SCM_RIGHTS. At this point, unix_inflight() can not happen because unix_gc_lock is already taken. Inflight graph remains unaffected.

Patch / fix

  • Linux Linux 4.19.314, 5.4.275, 5.10.216, 5.15.156, 6.1.87, 6.6.28, 6.8.7, 6.9
  • Siemens RUGGEDCOM RST2428P V3.1
  • Siemens SCALANCE XCM-/XRM-/XCH-/XRH-300 family V3.1
  • Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP V3.1.5
  • Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP V3.1.5
  • Siemens SIMATIC S7-1500 TM MFP - GNU/Linux subsystem V1.1.1
  • Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP V3.1.5
  • linux Debian 12 6.1.90-1
  • linux Debian 14, Debian 13 6.8.9-1

debian advisories DEBIAN-CVE-2024-26923

  • linux Ubuntu 20.04 LTS 5.4.0-189.209
  • linux Ubuntu 22.04 LTS 5.15.0-116.126
  • linux Ubuntu 24.04 LTS 6.8.0-38.38
  • linux-aws Ubuntu 20.04 LTS 5.4.0-1128.138
  • linux-aws Ubuntu 22.04 LTS 5.15.0-1065.71
  • linux-aws Ubuntu 24.04 LTS 6.8.0-1011.12
  • linux-gcp Ubuntu 20.04 LTS 5.4.0-1132.141
  • linux-gcp Ubuntu 22.04 LTS 5.15.0-1064.72

ubuntu advisories UBUNTU-CVE-2024-26923

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 5.14.0-427.42.1.el9_4
  • rv RHEL 9 5.14.0-427.42.1.el9_4
  • perf RHEL 9 5.14.0-427.42.1.el9_4
  • rtla RHEL 9 5.14.0-427.42.1.el9_4
  • bpftool RHEL 9 7.3.0-427.42.1.el9_4
  • libperf RHEL 9 5.14.0-427.42.1.el9_4
  • kernel-rt RHEL 9 5.14.0-427.42.1.el9_4
  • kernel-64k RHEL 9 5.14.0-427.42.1.el9_4

red hat advisories RHSA-2024:8617RHSA-2024:7486RHSA-2024:6993RHSA-2024:7000RHSA-2024:7001RHSA-2024:4823

  • kernel-rt Linux Micro 6.0 6.4.0-9.1
  • kernel-source-rt Linux Micro 6.0 6.4.0-9.1
  • kernel-source Linux Micro 6.0 6.4.0-18.1
  • kernel-default Linux Micro 6.0 6.4.0-18.1
  • kernel-kvmsmall Linux Micro 6.0 6.4.0-18.1
  • kernel-default-base Linux Micro 6.0 6.4.0-17.1.1.51
  • kernel-livepatch-SLE15-SP5_Update_10 SLE Live Patching 15 SP5 13-150500.11.8.1
  • kernel-livepatch-SLE15-SP4_Update_26 SLE Live Patching 15 SP4 10-150400.9.6.1

suse advisories SUSE-SU-2025:20028-1SUSE-SU-2025:20008-1SUSE-SU-2025:0266-1SUSE-SU-2025:0264-1SUSE-SU-2025:0261-1SUSE-SU-2025:0260-1

  • kernel AlmaLinux 9 5.14.0-427.42.1.el9_4
  • rv AlmaLinux 9 5.14.0-427.42.1.el9_4
  • perf AlmaLinux 9 5.14.0-427.42.1.el9_4
  • rtla AlmaLinux 9 5.14.0-427.42.1.el9_4
  • bpftool AlmaLinux 9 7.3.0-427.42.1.el9_4
  • libperf AlmaLinux 9 5.14.0-427.42.1.el9_4
  • kernel-rt AlmaLinux 9 5.14.0-427.42.1.el9_4
  • kernel-64k AlmaLinux 9 5.14.0-427.42.1.el9_4

almalinux advisories ALSA-2024:8617ALSA-2024:7000ALSA-2024:7001

  • kernel Rocky Linux 8 4.18.0-553.22.1.el8_10
  • kernel Rocky Linux 9 5.14.0-427.42.1.el9_4
  • kernel-rt Rocky Linux 8 4.18.0-553.22.1.rt7.363.el8_10

rocky linux advisories RLSA-2024:7000RLSA-2024:8617RLSA-2024:7001

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-2024-26923 updated cvss 7.0

kernel: af_unix: Fix garbage collector racing against connect()

  • 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
    affected: workaround, no fix planned “There are no known mitigations to this issue and updating to the latest Linux kernel version is recommended to address this vulnerability​.”
  • 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 “There are no known mitigations to this issue and updating to the latest Linux kernel version is recommended to address this vulnerability​.”
  • Red Hat CodeReady Linux Builder EUS (v.8.8) kernel-debuginfo-common-x86_64 4.18.0-477.74.1.el8_8, kernel-debuginfo-common-aarch64 4.18.0-477.74.1.el8_8, kernel-debuginfo-common-ppc64le 4.18.0-477.74.1.el8_8
    fixed: vendor fix “There are no known mitigations to this issue and updating to the latest Linux kernel version is recommended to address this vulnerability​.” RHSA-2024:6993
  • Red Hat CodeReady Linux Builder EUS (v.9.2) kernel-debuginfo-common-s390x 5.14.0-284.75.1.el9_2, kernel-debuginfo-common-x86_64 5.14.0-284.75.1.el9_2, kernel-debuginfo-common-aarch64 5.14.0-284.75.1.el9_2, kernel-debuginfo-common-ppc64le 5.14.0-284.75.1.el9_2
    fixed: vendor fix “There are no known mitigations to this issue and updating to the latest Linux kernel version is recommended to address this vulnerability​.” RHSA-2024:4823
  • Red Hat Enterprise Linux AppStream (v. 9) rv 5.14.0-427.42.1.el9_4, perf 5.14.0-427.42.1.el9_4, rtla 5.14.0-427.42.1.el9_4, kernel-devel-matched 5.14.0-427.42.1.el9_4, kernel-64k-devel-matched 5.14.0-427.42.1.el9_4, kernel-debug-devel-matched 5.14.0-427.42.1.el9_4, +6 more
    fixed: vendor fix “There are no known mitigations to this issue and updating to the latest Linux kernel version is recommended to address this vulnerability​.” RHSA-2024:8617
  • Red Hat Enterprise Linux AppStream EUS (v.9.2) perf 5.14.0-284.75.1.el9_2, rtla 5.14.0-284.75.1.el9_2, kernel-devel-matched 5.14.0-284.75.1.el9_2, kernel-64k-devel-matched 5.14.0-284.75.1.el9_2, kernel-debug-devel-matched 5.14.0-284.75.1.el9_2, kernel-debuginfo-common-s390x 5.14.0-284.75.1.el9_2, +5 more
    fixed: vendor fix “There are no known mitigations to this issue and updating to the latest Linux kernel version is recommended to address this vulnerability​.” RHSA-2024:4823
  • Red Hat Enterprise Linux BaseOS (v. 8) perf 4.18.0-553.22.1.el8_10, kernel 4.18.0-553.22.1.el8_10, bpftool 4.18.0-553.22.1.el8_10, kernel-core 4.18.0-553.22.1.el8_10, kernel-tools 4.18.0-553.22.1.el8_10, python3-perf 4.18.0-553.22.1.el8_10, +15 more
    fixed: vendor fix “There are no known mitigations to this issue and updating to the latest Linux kernel version is recommended to address this vulnerability​.” RHSA-2024:7000
  • Red Hat Enterprise Linux BaseOS (v. 9) bpftool 7.3.0-427.42.1.el9_4, kernel 5.14.0-427.42.1.el9_4, kernel-64k 5.14.0-427.42.1.el9_4, kernel-core 5.14.0-427.42.1.el9_4, kernel-tools 5.14.0-427.42.1.el9_4, python3-perf 5.14.0-427.42.1.el9_4, +28 more
    fixed: vendor fix “There are no known mitigations to this issue and updating to the latest Linux kernel version is recommended to address this vulnerability​.” RHSA-2024:8617
show 13 more
  • Red Hat Enterprise Linux BaseOS AUS (v.8.6) perf 4.18.0-372.125.1.el8_6, kernel 4.18.0-372.125.1.el8_6, bpftool 4.18.0-372.125.1.el8_6, kernel-core 4.18.0-372.125.1.el8_6, kernel-tools 4.18.0-372.125.1.el8_6, python3-perf 4.18.0-372.125.1.el8_6, +8 more Red Hat Enterprise Linux BaseOS E4S (v.8.6) perf 4.18.0-372.125.1.el8_6, kernel 4.18.0-372.125.1.el8_6, bpftool 4.18.0-372.125.1.el8_6, kernel-core 4.18.0-372.125.1.el8_6, kernel-tools 4.18.0-372.125.1.el8_6, python3-perf 4.18.0-372.125.1.el8_6, +15 more
    fixed: vendor fix “There are no known mitigations to this issue and updating to the latest Linux kernel version is recommended to address this vulnerability​.” RHSA-2024:7486
  • Red Hat Enterprise Linux BaseOS EUS (v.8.8) perf 4.18.0-477.74.1.el8_8, kernel 4.18.0-477.74.1.el8_8, bpftool 4.18.0-477.74.1.el8_8, kernel-core 4.18.0-477.74.1.el8_8, kernel-tools 4.18.0-477.74.1.el8_8, python3-perf 4.18.0-477.74.1.el8_8, +15 more
    fixed: vendor fix “There are no known mitigations to this issue and updating to the latest Linux kernel version is recommended to address this vulnerability​.” RHSA-2024:6993
  • Red Hat Enterprise Linux BaseOS EUS (v.9.2) bpftool 7.0.0-284.75.1.el9_2, kernel 5.14.0-284.75.1.el9_2, kernel-64k 5.14.0-284.75.1.el9_2, kernel-core 5.14.0-284.75.1.el9_2, kernel-tools 5.14.0-284.75.1.el9_2, python3-perf 5.14.0-284.75.1.el9_2, +28 more
    fixed: vendor fix “There are no known mitigations to this issue and updating to the latest Linux kernel version is recommended to address this vulnerability​.” RHSA-2024:4823
  • Red Hat Enterprise Linux BaseOS TUS (v.8.6) perf 4.18.0-372.125.1.el8_6, kernel 4.18.0-372.125.1.el8_6, bpftool 4.18.0-372.125.1.el8_6, kernel-core 4.18.0-372.125.1.el8_6, kernel-tools 4.18.0-372.125.1.el8_6, python3-perf 4.18.0-372.125.1.el8_6, +8 more
    fixed: vendor fix “There are no known mitigations to this issue and updating to the latest Linux kernel version is recommended to address this vulnerability​.” RHSA-2024:7486
  • Red Hat Enterprise Linux CRB (v. 8) kernel-debuginfo-common-x86_64 4.18.0-553.22.1.el8_10, kernel-debuginfo-common-aarch64 4.18.0-553.22.1.el8_10, kernel-debuginfo-common-ppc64le 4.18.0-553.22.1.el8_10
    fixed: vendor fix “There are no known mitigations to this issue and updating to the latest Linux kernel version is recommended to address this vulnerability​.” RHSA-2024:7000
  • Red Hat Enterprise Linux CRB (v. 9) libperf 5.14.0-427.42.1.el9_4, kernel-debuginfo-common-s390x 5.14.0-427.42.1.el9_4, kernel-debuginfo-common-x86_64 5.14.0-427.42.1.el9_4, kernel-debuginfo-common-aarch64 5.14.0-427.42.1.el9_4, kernel-debuginfo-common-ppc64le 5.14.0-427.42.1.el9_4
    fixed: vendor fix “There are no known mitigations to this issue and updating to the latest Linux kernel version is recommended to address this vulnerability​.” RHSA-2024:8617
  • Red Hat Enterprise Linux NFV (v. 8) kernel-rt 4.18.0-553.22.1.rt7.363.el8_10, kernel-rt-kvm 4.18.0-553.22.1.rt7.363.el8_10, kernel-rt-core 4.18.0-553.22.1.rt7.363.el8_10, kernel-rt-modules 4.18.0-553.22.1.rt7.363.el8_10, kernel-rt-debug-kvm 4.18.0-553.22.1.rt7.363.el8_10, kernel-rt-debug-core 4.18.0-553.22.1.rt7.363.el8_10, +4 more
    fixed: vendor fix “There are no known mitigations to this issue and updating to the latest Linux kernel version is recommended to address this vulnerability​.” RHSA-2024:7001
  • Red Hat Enterprise Linux NFV (v. 9) kernel-rt 5.14.0-427.42.1.el9_4, kernel-rt-kvm 5.14.0-427.42.1.el9_4, kernel-rt-core 5.14.0-427.42.1.el9_4, kernel-rt-modules 5.14.0-427.42.1.el9_4, kernel-rt-debug-kvm 5.14.0-427.42.1.el9_4, kernel-rt-debug-core 5.14.0-427.42.1.el9_4, +6 more
    fixed: vendor fix “There are no known mitigations to this issue and updating to the latest Linux kernel version is recommended to address this vulnerability​.” RHSA-2024:8617
  • Red Hat Enterprise Linux Real Time EUS (v.9.2) kernel-rt 5.14.0-284.75.1.rt14.360.el9_2, kernel-rt-core 5.14.0-284.75.1.rt14.360.el9_2, kernel-rt-modules 5.14.0-284.75.1.rt14.360.el9_2, kernel-rt-debug-core 5.14.0-284.75.1.rt14.360.el9_2, kernel-rt-modules-core 5.14.0-284.75.1.rt14.360.el9_2, kernel-rt-debug-modules 5.14.0-284.75.1.rt14.360.el9_2, +4 more Red Hat Enterprise Linux Real Time for NFV EUS (v.9.2) kernel-rt 5.14.0-284.75.1.rt14.360.el9_2, kernel-rt-kvm 5.14.0-284.75.1.rt14.360.el9_2, kernel-rt-core 5.14.0-284.75.1.rt14.360.el9_2, kernel-rt-modules 5.14.0-284.75.1.rt14.360.el9_2, kernel-rt-debug-kvm 5.14.0-284.75.1.rt14.360.el9_2, kernel-rt-debug-core 5.14.0-284.75.1.rt14.360.el9_2, +6 more
    fixed: vendor fix “There are no known mitigations to this issue and updating to the latest Linux kernel version is recommended to address this vulnerability​.” RHSA-2024:4831
  • Red Hat Enterprise Linux RT (v. 8) kernel-rt 4.18.0-553.22.1.rt7.363.el8_10, kernel-rt-core 4.18.0-553.22.1.rt7.363.el8_10, kernel-rt-modules 4.18.0-553.22.1.rt7.363.el8_10, kernel-rt-debug-core 4.18.0-553.22.1.rt7.363.el8_10, kernel-rt-debug-modules 4.18.0-553.22.1.rt7.363.el8_10, kernel-rt-modules-extra 4.18.0-553.22.1.rt7.363.el8_10, +2 more
    fixed: vendor fix “There are no known mitigations to this issue and updating to the latest Linux kernel version is recommended to address this vulnerability​.” RHSA-2024:7001
  • Red Hat Enterprise Linux RT (v. 9) kernel-rt 5.14.0-427.42.1.el9_4, kernel-rt-core 5.14.0-427.42.1.el9_4, kernel-rt-modules 5.14.0-427.42.1.el9_4, kernel-rt-debug-core 5.14.0-427.42.1.el9_4, kernel-rt-modules-core 5.14.0-427.42.1.el9_4, kernel-rt-debug-modules 5.14.0-427.42.1.el9_4, +4 more
    fixed: vendor fix “There are no known mitigations to this issue and updating to the latest Linux kernel version is recommended to address this vulnerability​.” RHSA-2024:8617
  • Red Hat OpenShift AI 8 rhoai/odh-rhel8-operator v2.13.1-2, rhoai/odh-dashboard-rhel8 v2.13.1-1, rhoai/odh-modelmesh-rhel8 v2.13.1-1, rhoai/odh-operator-bundle v2.13.1-2, rhoai/odh-rhel8-operator v2.14.0-24, rhoai/odh-dashboard-rhel8 v2.14.0-11, +56 more
    fixed: vendor fix “There are no known mitigations to this issue and updating to the latest Linux kernel version is recommended to address this vulnerability​.” RHBA-2024:8413
  • Red Hat Enterprise Linux AppStream EUS (v.9.2) kernel-doc 5.14.0-284.75.1.el9_2
    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-24-102-01 updated cvss 7.0

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 ICSA-25-226-15 updated cvss 7.0

Siemens SINEC OS

  • Siemens RUGGEDCOM RST2428P (6GK6242-6PA00) < 3.1 Siemens SCALANCE XCM-/XRM-/XCH-/XRH-300 family < 3.1
    affected: fixed in V3.1 support.industry.siemens.com
  • Siemens SCALANCE XC-300/XR-300/XC-400/XR-500WG/XR-500 family
    not affected

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

cisa ICSA-23-348-10 updated cvss 7.0

Siemens SIMATIC S7-1500

  • Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0) >= 3.1.0, < 3.1.5 Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0) >= 3.1.0, < 3.1.5 Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0) >= 3.1.0, < 3.1.5 Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0) >= 3.1.0, < 3.1.5 Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0) >= 3.1.0, < 3.1.5
    affected: fixed in V3.1.5, mitigation support.industry.siemens.com

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
2 y ago

Exploit prediction

0.21% chance of exploitation in the next 30 days, higher than 10% 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 4.7 CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H

Affected products

  • Linux Linux
  • Siemens RUGGEDCOM RST2428P
  • Siemens SCALANCE XC-300/XR-300/XC-400/XR-500WG/XR-500 family
  • Siemens SCALANCE XCM-/XRM-/XCH-/XRH-300 family
  • Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP
  • Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP
  • Siemens SIMATIC S7-1500 TM MFP - GNU/Linux subsystem
  • Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP

Classification

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