🛡️ CVE-2026-42140 — macro-plantuml-macro
Description
XWiki PlantUML Macro Vulnerable to Server-Side Request Forgery (SSRF) via 'server' parameter
Impact
The [PlantUML Macro](https://extensions.xwiki.org/xwiki/bin/view/Extension/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 affects all versions of the Plant UML Macro extension till version 2.4 included.
Patches
Version 2.4.1 of the Plant UML Macro extension fixes the issue by verifying if the supplied server domain matches one of the [trusted domain configured inside of XWiki](https://www.xwiki.org/xwiki/bin/view/Documentation/AdminGuide/Configuration/#HTrusteddomains).
Workarounds
Protect the XWiki server by placing it in a DMZ so that it cannot access any other internal servers.
Resources
The issue was fixed in [PLANTUML-25](https://jira.xwiki.org/browse/PLANTUML-25) by the commit [c8b19bda93058794e04c8862fc7ca85c59b5fe5c](https://github.com/xwiki-contrib/macro-plantuml/commit/c8b19bda93058794e04c8862fc7ca85c59b5fe5c).
For more information
If there are any questions or comments about this advisory:
- Open an issue in [JIRA XWiki.org](https://jira.xwiki.org/)
- Send an email to [Security Mailing List](mailto:[email protected])
Attribution
The issue was reported by Łukasz Rybak.
How this vulnerability can be exploited
This issue can be reached over the network, attack complexity is high, an attacker needs low-level privileges on the target. A user must be tricked into taking some action. The scope is changed, meaning a successful attack can affect components beyond the vulnerable one. Rated impact: confidentiality low, integrity low, availability none.
Weakness class
CVE-2026-42140 is classified as CWE-918: Server-Side Request Forgery (SSRF). The server fetches a URL supplied by the caller, which can be pointed at internal systems it alone can reach.
Affected software
CVE-2026-42140 is recorded against 2 packages.
- org.xwiki.contrib.plantuml:macro-plantuml-macro (fixed in 2.4.1)
- unknown
Timeline and source
Published on 5 May 2026. No public exploit is currently recorded for this entry. Record sourced from NVD.
References
github.com (Web)
nvd.nist.gov (Advisory)
github.com (Web)
github.com (Package)
jira.xwiki.org (Web)
Details
CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:L/I:L/A:N
Affected Packages
| Software | From version | Fixed in |
|---|---|---|
| org.xwiki.contrib.plantuml:macro-plantuml-macro | — | 2.4.1 |
| unknown | — | — |
References
More CVE 2026 advisories
Browse all of CVE 2026 in the advisory index.
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