CVE-2026-0858
CVE-2026-0858 is a Cross-site Scripting (XSS) vulnerability in net.sourceforge.plantuml:plantuml. O3 Security confirms whether CVE-2026-0858 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
PlantUML is vulnerable to Stored XSS due to insufficient sanitization of interactive attributes in GraphViz diagrams
Blast Radius
net.sourceforge.plantuml:plantumlReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.
Description
Versions of the package net.sourceforge.plantuml:plantuml before 1.2026.0 are vulnerable to Stored XSS due to insufficient sanitization of interactive attributes in GraphViz diagrams. As a result, a crafted PlantUML diagram can inject malicious JavaScript into generated SVG output, leading to arbitrary script execution in the context of applications that render the SVG.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | net.sourceforge.plantuml:plantuml | all versions | 1.2026.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for net.sourceforge.plantuml:plantuml. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update net.sourceforge.plantuml:plantuml to 1.2026.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-0858 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2026-0858 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2026-0858. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-0858 in your dependencies?
O3 detects CVE-2026-0858 across Maven dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.