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MEDIUM severity

CVE-2026-77606 — semantic-media-wiki

MEDIUM

CVE-2026-77606 is a medium-severity (CVSS 6.1) Cross-site Scripting (XSS) vulnerability in mediawiki/semantic-media-wiki. A fix is available for mediawiki/semantic-media-wiki — see the affected versions and patch details below.

Semantic MediaWiki has reflected XSS in Special:Ask plain table headers

Also known asGHSA-3jp5-3h47-28qf
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Nov 3, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

  • CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-77606.

EPSS Exploitation Probability

via FIRST.org ↗
0.3%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs18th percentile — riskier than 18% of all scored CVEsHighest risk
0.00%0.25%0.51%0.76%0.3%0.3%0.3%Oct 26Nov 26Nov 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected
🐘mediawiki/semantic-media-wiki

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.

Description

Failure mode

When headers=plain, table header text was emitted into <th> via a raw HTML path. User-controlled mainlabel content could therefore become executable HTML.

Remediation

  • TableResultPrinter now applies output-context escaping before passing plain headers to the table renderer.
  • The fix is limited to the HTML/plain-header branch so safe rendering modes are unaffected.

Why this is the right layer

The header value is not a structural token; it is display data. Sanitizing it at the sink is correct because the renderer owns the final HTML emission.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
🐘Packagistmediawiki/semantic-media-wikiall versions7.2.0composer require mediawiki/semantic-media-wiki:^7.2.0

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for mediawiki/semantic-media-wiki, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update mediawiki/semantic-media-wiki to 7.2.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-77606 is resolved across your whole dependency graph.

  3. Workarounds

    Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.

Frequently Asked Questions

#### Failure mode When `headers=plain`, table header text was emitted into `<th>` via a raw HTML path. User-controlled `mainlabel` content could therefore become executable HTML. #### Remediation - `TableResultPrinter` now applies output-context escaping before passing plain headers to the table renderer. - The fix is limited to the HTML/plain-header branch so safe rendering modes are unaffected. #### Why this is the right layer The header value is not a structural token; it is display data. Sanitizing it at the sink is correct because the renderer owns the final HTML emission.
O3 Security · Impact-Aware SCA

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CVE-2026-77606: semantic-media-wiki — Fixed in 7.2.0