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Fencer Intel
medium 6.1

CVE-2021-31551 json

An issue was discovered in the PageForms extension for MediaWiki through 1.35.2.

published 5y ago modified 4mo ago also BIT-mediawiki-2021-31551 , EUVD-2021-18448

cvss
6.1
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.9%
EPSS 0.9% chance of exploitation in 30 days, percentile 59%
public exploits
0
none known

Summary

An issue was discovered in the PageForms extension for MediaWiki through 1.35.2. Crafted payloads for Token-related query parameters allowed for XSS on certain PageForms-managed MediaWiki pages.

Patch / fix

  • bitnami mediawiki 1.35.3

Is CVE-2021-31551 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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Exploit prediction

0.90% chance of exploitation in the next 30 days, higher than 59% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
NVD 3.1 6.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
NVD 2.0 4.3 AV:N/AC:M/Au:N/C:N/I:P/A:N
OSV 3.1 6.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Affected packages

ecosystem package affected fixed in
bitnami mediawiki
<1.35.3
1.35.3

Classification

Weakness
  • CWE-79 Improper Neutralization of Input During Web Page Generation

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.