CVE-2021-25978 Apostrophe - XSS
Attackers can execute arbitrary JavaScript in victim browsers by uploading malicious SVG files to the Apostrophe CMS Images module.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2021-25978?
CVE-2021-25978 is a medium-severity cross-site scripting vulnerability in Apostrophe , published on 7 Nov 2021. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Official description
Apostrophe CMS versions between 2.63.0 to 3.3.1 are vulnerable to Stored XSS where an editor uploads an SVG file that contains malicious JavaScript onto the Images module, which triggers XSS once viewed.
Weakness: CWE-79
Which versions are affected by CVE-2021-25978?
2 open source packages ship an affected version, including apostrophe. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
apostrophe npm | From 2.63.0 | 3.4.0 |
apostrophe npm | From 2.63.0 | 3.4.0 |
Products include Apostrophecms Apostrophecms.
How do I fix CVE-2021-25978?
Upgrade apostrophe to 3.4.0 or later.
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-2021-25978 being exploited?
There is no known exploitation of CVE-2021-25978 in the wild and no public exploit code.
Other vulnerabilities in Apostrophe
- CVE-2021-25979 Apostrophe - Insufficient Session Expiration
- CVE-2026-35569 ApostropheCMS: Stored XSS in SEO Fields Leads to Authenticated API Data Exposure in ApostropheCMS
- CVE-2026-32730 ApostropheCMS MFA/TOTP Bypass via Incorrect MongoDB Query in Bearer Token Middleware
- CVE-2026-40186 ApostropheCMS: sanitize-html allowedTags Bypass via Entity-Decoded Text in nonTextTags Elements
- CVE-2026-33889 ApostropheCMS: Stored XSS via CSS Custom Property Injection in `@apostrophecms/color-field` Escaping Style Tag Context
Sources
Also known as GHSA-4r9c-jghc-cx5m.