No exploitation reportedFix available

CVE-2021-44858

Q: Is CVE-2021-44858 actively exploited?

Active exploitation of CVE-2021-44858 has not been confirmed. Its EPSS score was 1.4% on 2026-10-23, the estimated probability of exploitation in the next 30 days.

Q: What is the CVSS score for CVE-2021-44858?

CVE-2021-44858 has a CVSS v3 base score of 7.5 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N.

No exploitation reported by the sources we read.

Published2021-12-20
Fixed in1.37.1 · 1.36.3 · 1.35.5
WeaknessCWE-276

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

An issue was discovered in MediaWiki before 1.35.5, 1.36.x before 1.36.3, and 1.37.x before 1.37.1. It is possible to use action=edit&undo= followed by action=mcrundo and action=mcrrestore to view private pages on a private wiki that has at least one page set in $wgWhitelistRead.

Timeline

dates in UTC

2021-12-2009:15CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-10-23 21:37 UTC

Indicators tagged with this CVE, per day0 indicators over 7 days

Block these indicators

Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2021-44858?format=txt
CSV export: https://api.ismalicious.com/edl/cve/CVE-2021-44858?format=csv
TAXII collection of exploited CVEs
The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD · OSV

Mediawiki

Branch	Affected	Fixed in	Source
1.37	≥ 1.37.0, < 1.37.1	1.37.1	NVD · OSV
1.36	≥ 1.36.0, < 1.36.3	1.36.3	NVD · OSV
1.35	< 1.35.5	1.35.5	NVD · OSV

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Fix

Update Mediawiki to 1.37.1 · 1.36.3 · 1.35.5

Advisories and patches

phabricator.wikimedia.orgPatch · Vendor Advisory
www.mediawiki.orgMitigation · Vendor Advisory

Detection

Nuclei template: none so far
Exploit-DB: no entry
Proof-of-concept repositories: none listed

Sources

NVDCVSS 3.17.5read 2026-10-23
NVDCVSS 2.05read 2026-10-23
NVDweakness (CWE)CWE-276read 2026-10-23
FIRST EPSSEPSS score1.4 %2026-10-23
OSVaffected packages—

Technical details

CVSS v3 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Published: 2021-12-20
Last Modified: 2026-06-17
NVD status: Modified

Frequently asked questions

What is CVE-2021-44858?

Is CVE-2021-44858 actively exploited?

Active exploitation of CVE-2021-44858 has not been confirmed. Its EPSS score was 1.4% on 2026-10-23, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2021-44858?

CVE-2021-44858 has a CVSS v3 base score of 7.5 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N.

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