How severe is CVE-2026-39934?

CVE-2026-39934 has a CVSS 4.0 base score of 6.9, rated medium severity.

Is CVE-2026-39934 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (27th percentile), an estimate of the probability of exploitation in the next 30 days.

How do I fix CVE-2026-39934?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2026-39934 have an EU (EUVD) identifier?

Yes. CVE-2026-39934 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-19978.

When was CVE-2026-39934 published?

CVE-2026-39934 was published on 2026-04-07 and last updated on 2026-06-17.

CVE-2026-39934

CVE-2026-39934 is a medium-severity vulnerability with a CVSS 4.0 base score of 6.9. 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-835.

Key facts

Severity: Medium (CVSS 4.0 base score 6.9)
EPSS exploit prediction: 0% (27th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-19978
Weakness: CWE-835
Published: 2026-04-07
Last modified: 2026-06-17

Description

Loop with unreachable exit condition ('infinite loop') vulnerability in The Wikimedia Foundation Mediawiki - GrowthExperiments Extension allows Leveraging Time-of-Check and Time-of-Use (TOCTOU) Race Conditions. This issue was remediated only on the `master` branch.

Frequently asked questions

What is CVE-2026-39934?: Loop with unreachable exit condition ('infinite loop') vulnerability in The Wikimedia Foundation Mediawiki - GrowthExperiments Extension allows Leveraging Time-of-Check and Time-of-Use (TOCTOU) Race Conditions. This issue was remediated only on the `master` branch.
How severe is CVE-2026-39934?: CVE-2026-39934 has a CVSS 4.0 base score of 6.9, rated medium severity.
Is CVE-2026-39934 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (27th percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2026-39934?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-39934 have an EU (EUVD) identifier?: Yes. CVE-2026-39934 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-19978.
When was CVE-2026-39934 published?: CVE-2026-39934 was published on 2026-04-07 and last updated on 2026-06-17.

References

Other CWE-835 (Loop with Unreachable Exit Condition (Infinite Loop)) vulnerabilities

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CVE-2017-12990 — Critical (CVSS 9.8): The ISAKMP parser in tcpdump before 4.9.2 could enter an infinite loop due to bugs in print-isakmp.c, several functions.
CVE-2026-31448 — Critical (CVSS 9.4): In the Linux kernel, the following vulnerability has been resolved: ext4: avoid infinite loops caused by residual…

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