CVE-2026-42140 Server-Side Request Forgery (SSRF) in PlantUML Macro via 'server' parameter
An attacker can exploit the PlantUML Macro in XWiki to perform Server-Side Request Forgery by supplying unvalidated URLs, potentially accessing internal resources.
- 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-2026-42140?
CVE-2026-42140 is a medium-severity server-side request forgery vulnerability in xwiki-contrib macro-plantuml, published on 4 May 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Official description
PlantUML Macro is a macro for rendering UML diagrams from simple textual schemes. Prior to version 2.4.1, the PlantUML Macro is vulnerable to Server-Side Request Forgery (SSRF). The macro allows users to specify an alternative PlantUML server via the server parameter. However, the application does not validate the supplied URL. An attacker can supply an internal IP address or a malicious external URL. The XWiki server will attempt to connect to this URL to "render" the diagram. This issue has been patched in version 2.4.1.
Weakness: CWE-918
Which versions are affected by CVE-2026-42140?
2 open source packages ship an affected version, including org.xwiki.contrib.plantuml:macro-plantuml-macro.
| Package | Affected | Fixed in |
|---|---|---|
org.xwiki.contrib.plantuml:macro-plantuml-macro Maven | All versions | 2.4.1 |
org.xwiki.contrib.plantuml:macro-plantuml-macro Maven | All versions | 2.4.1 |
How do I fix CVE-2026-42140?
Upgrade org.xwiki.contrib.plantuml:macro-plantuml-macro to 2.4.1 or later.
Upgrade, and send outbound requests through an allow-list that blocks internal addresses. More about Server-side request forgery.
Is CVE-2026-42140 being exploited?
There is no known exploitation of CVE-2026-42140 in the wild and no public exploit code.
Sources
Also known as GHSA-42fc-7w97-8vrc.