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Semantic MediaWiki affected by Special:Ask table `sep` parameter reflected XSS

Moderate severity GitHub Reviewed Published Jul 18, 2026 in SemanticMediaWiki/SemanticMediaWiki • Updated Sep 18, 2026

Package

composer mediawiki/semantic-media-wiki (Composer)

Affected versions

<= 7.1.0

Patched versions

7.2.0

Description

Failure mode

sep was inserted verbatim into the HTML that joins a table cell's values. This made it possible to inject HTML through the separator value. The same unsanitised table HTML is produced both for the standard Special:Ask render and for its raw request output (request_type=raw), so the injection was reachable without authentication.

Remediation

  • In all non-wiki output modes (HTML, raw request, file), sep is escaped unless it is a safe <br> variant.
  • This preserves legitimate line-break separators while blocking markup injection.

Maintenance note

If the table renderer ever gains richer separator semantics, keep the whitelist explicit. Do not expand the allowed HTML surface casually.

References

@alistair3149 alistair3149 published to SemanticMediaWiki/SemanticMediaWiki Jul 18, 2026
Published to the GitHub Advisory Database Sep 18, 2026
Reviewed Sep 18, 2026
Last updated Sep 18, 2026

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
Required
Scope
Changed
Confidentiality
Low
Integrity
Low
Availability
None

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(16th percentile)

Weaknesses

Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. Learn more on MITRE.

CVE ID

CVE-2026-77607

GHSA ID

GHSA-7xv3-gf2g-498h

Source code

Credits

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