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Fencer Intel
medium 5.4

CVE-2026-126564 json

Semantic MediaWiki 2.5.0 before 7.4.1 Stored XSS via Special:Browse Factbox Title

published yesterday modified yesterday also EUVD-2026-123079 , GHSA-mc5x-2j7v-x8hp

Unreviewed: the maintainers' own advisory

Published by the maintainers on their GitHub repository SemanticMediaWiki/SemanticMediaWiki. GitHub has not reviewed it into the GitHub Advisory Database, so the affected packages and versions are the maintainers' word. Read the full advisory on GitHub.

cvss
5.4
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 13%
public exploits
0
none known

Summary

Semantic MediaWiki 2.5.0 before 7.4.1 contains a stored cross-site scripting vulnerability in ValueFormatter::getFormattedSubject() that renders property label segments after a literal   as unescaped markup. Users with page-edit rights can set a preferred property label containing an img onerror payload that executes when anyone, including administrators, views Special:Browse or the smwbrowse API.

Patch / fix

  • SemanticMediaWiki SemanticMediaWiki 7.4.1

Is CVE-2026-126564 in your stack? 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

0.22% chance of exploitation in the next 30 days, higher than 13% of all scored CVEs (FIRST EPSS, 2026-11-11).

CVSS scores

assigned by version score vector
CNA 4.0 5.1 CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N
CNA 3.1 5.4 CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
CNA 4.0 5.1 CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
NVD 3.1 5.4 CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

Affected products

  • SemanticMediaWiki SemanticMediaWiki

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.

The maintainers of SemanticMediaWiki/SemanticMediaWiki published their own advisory on GitHub. Reviewed sources take precedence over it.