CVE-2025-54881Public exploitNetwork attack vector

Cross-site scripting via unsanitized sequence labels

Published Aug 19, 2025 · Updated Aug 19, 2025

Cross-site scripting in Mermaid 10.9.0-rc.1 through 10.9.3 and 11.0.0-alpha.1 through 11.9.0 allows attackers to run script. The calculateMathMLDimensions method assigns a KaTeX-rendered sequence label to a temporary element's innerHTML without sanitization. A site must render an attacker-controlled sequence diagram with KaTeX support, after which the script executes in a user's browser context.

CVSS severity5.3
Medium
EPSS probability0.76%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Cross-site scripting in Mermaid 10.9.0-rc.1 through 10.9.3 and 11.0.0-alpha.1 through 11.9.0 allows attackers to run script. The calculateMathMLDimensions method assigns a KaTeX-rendered sequence label to a temporary element's innerHTML without sanitization. A site must render an attacker-controlled sequence diagram with KaTeX support, after which the script executes in a user's browser context.

The record

CVE
CVE-2025-54881
Published
Aug 19, 2025
Updated
Aug 19, 2025
Vendor
Mermaid
Product
Mermaid
Classifications
CWE-79, T1059.007
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 19, 2025CVE publishedPublication date reported by the CVE source.
  2. Aug 19, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=>= 10.9.0-rc.1, <= 11.9.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Mermaid · Mermaidversion=>= 10.9.0-rc.1, <= 11.9.0

Published CVSS scores

5.3GitHubCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1059.007Command and Scripting Interpreter: JavaScript/JScript

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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