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Fencer Vulns
critical 9.8

CVE-2023-39976 json

log_blackbox.c in libqb before 2.0.8 allows a buffer overflow via long log messages because the header size is not considered.

published 2023-08-08 3 y ago modified 2026-06-17 4 mo ago also EUVD-2023-43669

cvss
9.8
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
1.2%
EPSS 1.2% chance of exploitation in 30 days, percentile 67%
public exploits
0
none known

Summary

log_blackbox.c in libqb before 2.0.8 allows a buffer overflow via long log messages because the header size is not considered.

Patch / fix

  • clusterlabs libqb 2.0.8
  • libqb Debian 14, Debian 13 2.0.8-1

debian advisories DEBIAN-CVE-2023-39976

  • libqb Ubuntu 22.04 LTS 2.0.4-1ubuntu0.2

ubuntu advisories UBUNTU-CVE-2023-39976

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

  • libqb RHEL 9 2.0.6-4.el9_3
  • libqb RHEL 9.2 EUS 2.0.6-3.el9_2
  • libqb RHEL 9.0 EUS 2.0.3-12.el9_0

red hat advisories RHSA-2023:7376RHSA-2023:6578RHSA-2023:5597

  • libqb SLE Module for Basesystem 15 SP4, SLE High Availability Extension 15 SP4, openSUSE Leap 15.4 2.0.4+20211112.a2691b9-150400.4.3.1
  • libqb SLE Module for Basesystem 15 SP5, SLE High Availability Extension 15 SP5, openSUSE Leap 15.5 2.0.6+20220323.758044b-150500.3.3.1
  • libqb SLE High Availability Extension 15 SP2, SLE High Availability Extension 15 SP1, openSUSE Leap 15.4 1.0.3+20190326.a521604-150100.3.9.1
  • libqb SLE High Availability Extension 15 SP3 2.0.2+20201203.def947e-150300.3.6.1

suse advisories SUSE-SU-2023:3944-1SUSE-SU-2023:3897-1SUSE-SU-2023:3728-1SUSE-SU-2023:3727-1

  • libqb AlmaLinux 9 2.0.6-4.el9_3

almalinux advisories ALSA-2023:6578

  • libqb Azure Linux 3.0 2.0.8-1

azure linux advisories AZL-36957

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-2023-39976 updated cvss 7.2

libqb: Buffer overflow in log_blackbox.c

  • Red Hat Enterprise Linux 6 libqb Red Hat Enterprise Linux 7 libqb
    affected: no fix planned “Out of support scope”
  • Red Hat Enterprise Linux AppStream (v. 9) libqb 2.0.6-4.el9_3
    fixed: vendor fix RHSA-2023:6578
  • Red Hat Enterprise Linux AppStream EUS (v.9.0) libqb 2.0.3-12.el9_0
    fixed: vendor fix RHSA-2023:5597
  • Red Hat Enterprise Linux AppStream EUS (v.9.2) libqb 2.0.6-3.el9_2
    fixed: vendor fix RHSA-2023:7376
  • Red Hat Enterprise Linux High Availability (v. 9) libqb-devel 2.0.6-4.el9_3, libqb-debuginfo 2.0.6-4.el9_3, libqb-debugsource 2.0.6-4.el9_3, doxygen2man-debuginfo 2.0.6-4.el9_3, libqb-tests-debuginfo 2.0.6-4.el9_3
    fixed: vendor fix RHSA-2023:6578
  • Red Hat Enterprise Linux High Availability EUS (v.9.0) libqb-devel 2.0.3-12.el9_0, libqb-debuginfo 2.0.3-12.el9_0, libqb-debugsource 2.0.3-12.el9_0, doxygen2man-debuginfo 2.0.3-12.el9_0, libqb-tests-debuginfo 2.0.3-12.el9_0
    fixed: vendor fix RHSA-2023:5597
  • Red Hat Enterprise Linux High Availability EUS (v.9.2) libqb-devel 2.0.6-3.el9_2, libqb-debuginfo 2.0.6-3.el9_2, libqb-debugsource 2.0.6-3.el9_2, doxygen2man-debuginfo 2.0.6-3.el9_2, libqb-tests-debuginfo 2.0.6-3.el9_2
    fixed: vendor fix RHSA-2023:7376
  • Red Hat Enterprise Linux Resilient Storage (v. 9) libqb-devel 2.0.6-4.el9_3, libqb-debuginfo 2.0.6-4.el9_3, libqb-debugsource 2.0.6-4.el9_3, doxygen2man-debuginfo 2.0.6-4.el9_3, libqb-tests-debuginfo 2.0.6-4.el9_3
    fixed: vendor fix RHSA-2023:6578
show 3 more
  • Red Hat Enterprise Linux Resilient Storage EUS (v.9.0) libqb-devel 2.0.3-12.el9_0, libqb-debuginfo 2.0.3-12.el9_0, libqb-debugsource 2.0.3-12.el9_0, doxygen2man-debuginfo 2.0.3-12.el9_0, libqb-tests-debuginfo 2.0.3-12.el9_0
    fixed: vendor fix RHSA-2023:5597
  • Red Hat Enterprise Linux Resilient Storage EUS (v.9.2) libqb-devel 2.0.6-3.el9_2, libqb-debuginfo 2.0.6-3.el9_2, libqb-debugsource 2.0.6-3.el9_2, doxygen2man-debuginfo 2.0.6-3.el9_2, libqb-tests-debuginfo 2.0.6-3.el9_2
    fixed: vendor fix RHSA-2023:7376
  • Red Hat Enterprise Linux 8 libqb
    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
2 y ago

Exploit prediction

1.18% chance of exploitation in the next 30 days, higher than 67% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

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

Classification

Weakness
  • CWE-120 Buffer Copy without Checking Size of Input

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.