CVE-2021-44857Network attack vector

Arbitrary page overwrite via missing edit checks

Published Dec 17, 2021 · Updated Aug 4, 2024

Improper authorization in affected MediaWiki releases allows remote authenticated users to overwrite arbitrary wiki pages through MCR actions. The action=mcrundo and action=mcrrestore handlers fail to check edit permissions, so they accept an arbitrary revision and save its content to an attacker-chosen page. Any public wiki is exposed; a private wiki is exposed when at least one page is allowed by $wgWhitelistRead or $wgWhitelistReadRegexp, and unauthorized writes remain visible in page history.

CVSS severity6.5
Medium
EPSS probability0.87%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper authorization in affected MediaWiki releases allows remote authenticated users to overwrite arbitrary wiki pages through MCR actions. The action=mcrundo and action=mcrrestore handlers fail to check edit permissions, so they accept an arbitrary revision and save its content to an attacker-chosen page. Any public wiki is exposed; a private wiki is exposed when at least one page is allowed by $wgWhitelistRead or $wgWhitelistReadRegexp, and unauthorized writes remain visible in page history.

The record

CVE
CVE-2021-44857
Published
Dec 17, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-862, T1565.001
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Dec 17, 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

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

4.0NIST NVDAV:N/AC:L/Au:S/C:N/I:P/A:N
6.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N

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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-862Missing Authorization
T1565.001Stored Data Manipulation

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

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Your stack

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