CVE-2021-41800Network attack vector

Service interruption via unguarded contributions query

Published Oct 11, 2021 · Updated Aug 4, 2024

Resource exhaustion in MediaWiki before 1.36.2 allows remote attackers to degrade service availability via Special:Contributions. SpecialContributions::execute calls the pager getNumRows method before entering PoolCounterWorkViaCallback, causing the database query to run outside the concurrency guard. Unauthenticated access to the page is sufficient to start a lengthy SQL query that consumes database resources and degrades service availability.

CVSS severity5.3
Medium
EPSS probability1.81%
Next 30 days · Sep 17, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Resource exhaustion in MediaWiki before 1.36.2 allows remote attackers to degrade service availability via Special:Contributions. SpecialContributions::execute calls the pager getNumRows method before entering PoolCounterWorkViaCallback, causing the database query to run outside the concurrency guard. Unauthenticated access to the page is sufficient to start a lengthy SQL query that consumes database resources and degrades service availability.

The record

CVE
CVE-2021-41800
Published
Oct 11, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-770, T1499.003
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Oct 11, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

5.0NIST NVDAV:N/AC:L/Au:N/C:N/I:N/A:P
5.3NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 11, 2026Sep 17, 2026
Latest reporting daySep 17, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-770Allocation of Resources Without Limits or Throttling
T1499.003Application Exhaustion Flood

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo