CVE-2026-0858: Versions of the package net.sourceforge.plantuml:plantuml before 1.2026.0 are vulnerable to Stored XSS due to

Q: How do I fix CVE-2026-0858?

plantuml: upgrade to 1.2026.0. Exact commands for each OS are on this page.

Q: Is CVE-2026-0858 being exploited?

CVE-2026-0858 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-0858 affect?

CVE-2026-0858 affects plantuml. Severity is medium (CVSS 6.1). 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 malic

Q: How urgent is CVE-2026-0858?

Priority 28/100. No elevated risk signals yet.

Routine

MEDIUM 6.1UPGRADE

CVE-2026-0858 is a medium-severity flaw (CVSS 6.1) affecting plantuml. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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.

Why this priority

No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score	6.1 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.3% (top 73%)
CISA exploited list	No
Weakness	CWE-79
Published	2026-01-16
Last modified	2026-06-17

Publisher (CNA): Snyk · Vendor: plantuml

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-01-16 05:16 UTCPublished CVE record published
2026-06-17 10:11 UTCUpdated Record last modified

plantuml plantuml UPGRADE

Affected: < 1.2026.0

Fixed in: 1.2026.0

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy plantuml || rpm -q plantuml || plantuml --version

2. UPGRADE to 1.2026.0 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade plantuml

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade plantuml

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-0858?

plantuml: upgrade to 1.2026.0. Exact commands for each OS are on this page.

Is CVE-2026-0858 being exploited?

CVE-2026-0858 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-0858 affect?

CVE-2026-0858 affects plantuml. Severity is medium (CVSS 6.1). 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 malic

How urgent is CVE-2026-0858?

Priority 28/100. No elevated risk signals yet.

References

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