How severe is CVE-2023-39976?

CVE-2023-39976 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2023-39976 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (58th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2023-39976?

CVE-2023-39976 affects Clusterlabs Libqb. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2023-39976?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

When was CVE-2023-39976 published?

CVE-2023-39976 was published on 2023-08-08 and last updated on 2026-06-17.

CVE-2023-39976

CVE-2023-39976 is a critical-severity vulnerability in Clusterlabs Libqb with a CVSS 3.x base score of 9.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-120.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
EPSS exploit prediction: 1% (58th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-120
Affected product: Clusterlabs Libqb
Published: 2023-08-08
Last modified: 2026-06-17

Description

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

Frequently asked questions

What is CVE-2023-39976?: log_blackbox.c in libqb before 2.0.8 allows a buffer overflow via long log messages because the header size is not considered.
How severe is CVE-2023-39976?: CVE-2023-39976 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2023-39976 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (58th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2023-39976?: CVE-2023-39976 affects Clusterlabs Libqb. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2023-39976?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2023-39976 published?: CVE-2023-39976 was published on 2023-08-08 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:clusterlabs:libqb:*:*:*:*:*:*:*:*

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