HOMEVULNERABILITIESCVE-2021-36126
CRITICAL

CVE-2021-36126

NVD-CWE-OtherPublished: July 2, 2021· Updated: Jun 17, 2026

9.8
CVSS v3.1

Official Description

An issue was discovered in the AbuseFilter extension in MediaWiki through 1.36. If the MediaWiki:Abusefilter-blocker message is invalid within the content language, the filter user falls back to the English version, but that English version could also be invalid on a wiki. This would result in a fatal error, and potentially fail to block or restrict a potentially nefarious user.

NVD Source

Technical Analysis

CVE-2021-36126 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

A successful exploit results in complete confidentiality breach (data exposure), full integrity compromise (data manipulation), availability disruption (denial of service), with a CVSS base score of 9.8.

CVSS v3.1 Vector Breakdown

Exploitability
Attack VectorNetwork
Attack ComplexityLow
Privileges Req.None
User InteractionNone
ScopeUnchanged
Impact
ConfidentialityHigh
IntegrityHigh
AvailabilityHigh
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected Vendors & Products

mediawiki1 product(s)
mediawiki
Source: NVD CPE · 1 total CPE entries

Exploit & PoC Resources

NO KNOWN EXPLOITNo public exploit confirmed at this time
Exploit-DB
Offensive Security exploit database
GitHub PoC Search
Community PoC repositories
Rapid7 / Metasploit
Metasploit module search
PacketStorm
Security advisories & exploits
NVD Detail
Official NIST entry
MITRE CVE
CVE Program entry
External links open in a new tab. Always verify in a controlled environment before use.

Official Patches & Advisories

PATCHhttps://gerrit.wikimedia.org/r/q/I9e9f44b7663e810de70fb9ac7f6760f83dd4895b
PATCHhttps://phabricator.wikimedia.org/T284364
PATCHhttps://gerrit.wikimedia.org/r/q/I9e9f44b7663e810de70fb9ac7f6760f83dd4895b
PATCHhttps://phabricator.wikimedia.org/T284364

All References (4)

→
https://gerrit.wikimedia.org/r/q/I9e9f44b7663e810de70fb9ac7f6760f83dd4895bPatch · Vendor Advisory
→
https://phabricator.wikimedia.org/T284364Exploit · Issue Tracking · Patch · Vendor Advisory
→
https://gerrit.wikimedia.org/r/q/I9e9f44b7663e810de70fb9ac7f6760f83dd4895bPatch · Vendor Advisory
→
https://phabricator.wikimedia.org/T284364Exploit · Issue Tracking · Patch · Vendor Advisory

Quick Facts

CVE IDCVE-2021-36126
CVSS Score9.8 / 10
SeverityCRITICAL
WeaknessNVD-CWE-Other
CISA KEVNo
Affected1 vendor(s)
PublishedJul 2, 2021

Related CVEs (NVD-CWE-Other)

CVE-1999-1405
10.0
CVE-2002-1468
10.0
CVE-2007-1015
10.0
CVE-2001-1080
10.0
CVE-1999-0208
10.0
CVE-2002-0747
10.0

Recommended Actions

  • →Apply vendor patches immediately
  • →Monitor CVE-2021-36126 in threat intel feeds
  • →Review IDS/IPS signatures for exploitation attempts
Data sourced from NVD (NIST), CISA KEV, and EPSS (FIRST). Analysis generated by CTIWatch. CVE data is provided under the NVD usage policy.
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