CVE-2026-44898Public exploitNetwork attack vector

Cross-site scripting via unescaped TOC anchor IDs

Published May 26, 2026 · Updated May 26, 2026

Cross-site scripting in Mistune before 3.2.1 allows remote attackers to execute script in rendered TOCs via crafted headings. The render_toc_ul() function formats an unescaped heading ID directly into an anchor href, letting a quote terminate the attribute and inject HTML. Exploitation requires an application to derive IDs from untrusted heading text and a victim to view the generated TOC, exposing browser-accessible data and DOM integrity.

CVSS severity6.1
Medium
EPSS probability0.23%
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 Mistune before 3.2.1 allows remote attackers to execute script in rendered TOCs via crafted headings. The render_toc_ul() function formats an unescaped heading ID directly into an anchor href, letting a quote terminate the attribute and inject HTML. Exploitation requires an application to derive IDs from untrusted heading text and a victim to view the generated TOC, exposing browser-accessible data and DOM integrity.

The record

CVE
CVE-2026-44898
Published
May 26, 2026
Updated
May 26, 2026
Vendor
Lepture
Product
Mistune
Classifications
CWE-79, CAPEC-63, T1059.007
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 26, 2026CVE publishedPublication date reported by the CVE source.
  2. May 26, 2026Record 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=< 3.2.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Lepture · Mistuneversion=< 3.2.1

Published CVSS scores

6.1GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A: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')
CAPEC-63Cross-Site Scripting (XSS)
T1059.007JavaScript/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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