What is CVE-2026-0858?

CVE-2026-0858 is a medium-severity vulnerability in Plantuml, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2026-01-16.

How severe is CVE-2026-0858?

Medium severity. CVSS v3 base score is 6.1 out of 10.

XSS in Plantuml

CVE-2026-0858

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.

Vulnerability class: XSS (Cross-Site Scripting)

Published 2026-01-16 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 6.1 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N.

EPSS exploit prediction

EPSS: 0.003 (25.8th percentile), scored 2026-10-10.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 26th percentile — 25.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.003 · newest: 0.003 · change: +0.000

Affected products

Plantuml
Net.sourceforge.plantuml:plantuml — versions 0

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

References

security.snyk.io/vuln/SNYK-JAVA-NETSOURCEFORGEPLANTUML-14552230 (Patch, Vendor Advisory)
github.com/plantuml/plantuml/commit/6826315db092d2e432aeab1a0894e08017c6e4bd (Patch)
github.com/plantuml/plantuml/releases/tag/v1.2026.0 (Release Notes)

Frequently asked questions

What is CVE-2026-0858?: CVE-2026-0858 is a medium-severity vulnerability in Plantuml, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2026-01-16.
How severe is CVE-2026-0858?: Medium severity. CVSS v3 base score is 6.1 out of 10.