How severe is CVE-2023-37303?

CVE-2023-37303 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-2023-37303 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (57th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2023-37303?

CVE-2023-37303 affects Mediawiki. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2023-37303?

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-2023-37303 published?

CVE-2023-37303 was published on 2023-06-30 and last updated on 2026-06-17.

CVE-2023-37303

CVE-2023-37303 is a critical-severity vulnerability in Mediawiki 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-754.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
EPSS exploit prediction: 1% (57th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-754
Affected product: Mediawiki
Published: 2023-06-30
Last modified: 2026-06-17

Description

An issue was discovered in the CheckUser extension for MediaWiki through 1.39.3. In certain situations, an attempt to block a user fails after a temporary browser hang and a DBQueryDisconnectedError error message.

Frequently asked questions

What is CVE-2023-37303?: An issue was discovered in the CheckUser extension for MediaWiki through 1.39.3. In certain situations, an attempt to block a user fails after a temporary browser hang and a DBQueryDisconnectedError error message.
How severe is CVE-2023-37303?: CVE-2023-37303 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-2023-37303 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (57th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2023-37303?: CVE-2023-37303 affects Mediawiki. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2023-37303?: 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-2023-37303 published?: CVE-2023-37303 was published on 2023-06-30 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:mediawiki:mediawiki:*:*:*:*:*:*:*:*

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