HOMEVULNERABILITIESCVE-2021-31556
CRITICAL

CVE-2021-31556

CWE-1284Published: August 12, 2021· Updated: Jun 17, 2026

9.8
CVSS v3.1

Official Description

An issue was discovered in the Oauth extension for MediaWiki through 1.35.2. MWOAuthConsumerSubmitControl.php does not ensure that the length of an RSA key will fit in a MySQL blob.

NVD Source

Technical Analysis

CVE-2021-31556 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

Fedora1 product(s)
fedora
mediawiki1 product(s)
mediawiki
Source: NVD CPE · 4 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/I13ff0350a9a0a3cd5ab3e1f82dd0d8d9c13cf9e9
PATCHhttps://gerrit.wikimedia.org/r/q/I13ff0350a9a0a3cd5ab3e1f82dd0d8d9c13cf9e9
ADVISORYhttps://phabricator.wikimedia.org/T277380
ADVISORYhttps://phabricator.wikimedia.org/T277380

All References (10)

→
https://gerrit.wikimedia.org/r/q/I13ff0350a9a0a3cd5ab3e1f82dd0d8d9c13cf9e9Patch · Vendor Advisory
→
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/CJDYJQWT43GBD6GNQ4OW7JOZ6WQ6DZTN/
→
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/MDBPECBWN6LWNSWIQMVXK6PP4YFEUYHA/
→
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/QNEAI2T3Y65I55ZB6UE6RMC662RZTGRX/
→
https://phabricator.wikimedia.org/T277380Permissions Required · Vendor Advisory
→
https://gerrit.wikimedia.org/r/q/I13ff0350a9a0a3cd5ab3e1f82dd0d8d9c13cf9e9Patch · Vendor Advisory
→
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/CJDYJQWT43GBD6GNQ4OW7JOZ6WQ6DZTN/
→
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/MDBPECBWN6LWNSWIQMVXK6PP4YFEUYHA/
→
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/QNEAI2T3Y65I55ZB6UE6RMC662RZTGRX/
→
https://phabricator.wikimedia.org/T277380Permissions Required · Vendor Advisory

Quick Facts

CVE IDCVE-2021-31556
CVSS Score9.8 / 10
SeverityCRITICAL
WeaknessCWE-1284
CISA KEVNo
Affected2 vendor(s)
PublishedAug 12, 2021

Related CVEs (CWE-1284)

CVE-2026-49777
KEV10.0
CVE-2026-25345
9.9
CVE-2008-2374
9.8
CVE-2022-20385
9.8
CVE-2025-55398
9.8
CVE-2025-43964
9.8

Recommended Actions

  • →Apply vendor patches immediately
  • →Monitor CVE-2021-31556 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.COM. CVE data is provided under the NVD usage policy.
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