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Vulnerabilities

Vulnerability · CVE-2026-30977

RenderBlocking is a MediaWiki extension that allows interface administrators to specify render-blocking CSS and JavaScript.

Published Mar 10, 2026 · catalog updated Jun 17, 2026 · RenderBlocking is a MediaWiki

Check if you run it

No confirmed exploitation is on record for CVE-2026-30977. EPSS is 0.51%. Act only if a listed version of RenderBlocking is a MediaWiki is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (RenderBlocking is a MediaWiki).
  • No version range is stored. A customer cannot check an installed version against this record.
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
Low2.0
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.51%
Remediation
Advisory link
Affected products
See sources for product scope

RenderBlocking is a MediaWiki extension that allows interface administrators to specify render-blocking CSS and JavaScript. Prior to 0.1.1, there is Stored XSS in renderblocking-css with Inline Assets mode. $wgRenderBlockingInlineAssets = true and editsitecss user rights are required. This vulnerability is fixed in 0.1.1.

No affected version ranges are stored yet. Use the vendor advisory before you decide this record does not apply.

How to fix CVE-2026-30977

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-30977. EPSS is 0.51%. Act only if a listed version of RenderBlocking is a MediaWiki is installed.

Which versions are affected?

Affected version ranges are not on this record. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-79: Cross-site Scripting (XSS). EPSS 0.51%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Mar 10, 2026 · NIST NVD

    Detected

    RenderBlocking is a MediaWiki extension that allows interface administrators to specify render-blocking CSS and JavaScript. Prior to 0.1.1, there is Stored XSS in renderblocking-css with Inline Assets mode. $wgRenderBlockingInlineAssets = true and editsitecss user rights are required. This vulnerability is fixed in 0.1.1.

  2. Jun 17, 2026 · NIST NVD

    Updated

    RenderBlocking is a MediaWiki extension that allows interface administrators to specify render-blocking CSS and JavaScript. Prior to 0.1.1, there is Stored XSS in renderblocking-css with Inline Assets mode. $wgRenderBlockingInlineAssets = true and editsitecss user rights are required. This vulnerability is fixed in 0.1.1.

Sources

  • CVE.orgVulnerability recordCVE-2026-30977

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-30977

    30-day exploitation probability 0.5%

    first.org
  • NIST NVDVulnerability recordCVE-2026-30977

    RenderBlocking is a MediaWiki extension that allows interface administrators to specify render-blocking CSS and JavaScript. Prior to 0.1.1, there is Stored XSS in renderblocking-css with Inline Assets mode. $wgRenderBlockingInlineAssets = true and editsitecss user rights are requ

    nvd.nist.gov

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.