CVE-2026-30977 RenderBlocking has Stored XSS in renderblocking-css with Inline Assets mode
Stored XSS in RenderBlocking extension allows attackers to execute scripts when Inline Assets mode is enabled and user has edit rights.
- Exploited in the wild
- Not known
- Login needed
- An administrator
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2026-30977?
CVE-2026-30977 is a low-severity cross-site scripting vulnerability in lihaohong6 RenderBlocking, published on 10 Mar 2026. An attacker needs administrator access to exploit it, and only if a user opens a file or follows a link.
Official description
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.
Weakness: CWE-79
Which versions are affected by CVE-2026-30977?
How do I fix CVE-2026-30977?
No fix has been published for CVE-2026-30977 yet. Limit exposure of the affected software until one is available.
Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.
Is CVE-2026-30977 being exploited?
There is no known exploitation of CVE-2026-30977 in the wild and no public exploit code.
Sources
Also known as GHSA-4h5r-8rjm-496r.