CVE-2026-54889Public exploitNetwork attack vector

Cross-site scripting via unsanitized Delta URLs

Published Jun 29, 2026 · Updated Jun 29, 2026

Cross-site scripting in MDEx 0.8.3 through 0.13.1 allows remote attackers to execute browser script through crafted Markdown URLs. MDEx.DeltaConverter.default_convert_node/3 copies link, wikilink, and image URLs into Quill Delta attributes without scheme validation. Exploitation requires an application to convert attacker-controlled Markdown to Delta and a viewer to click a rendered javascript link, enabling actions in that viewer's browser context.

CVSS severity5.1
Medium
EPSS probability0.54%
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 MDEx 0.8.3 through 0.13.1 allows remote attackers to execute browser script through crafted Markdown URLs. MDEx.DeltaConverter.default_convert_node/3 copies link, wikilink, and image URLs into Quill Delta attributes without scheme validation. Exploitation requires an application to convert attacker-controlled Markdown to Delta and a viewer to click a rendered javascript link, enabling actions in that viewer's browser context.

The record

CVE
CVE-2026-54889
Published
Jun 29, 2026
Updated
Jun 29, 2026
Vendor
Leandro Pereira
Product
MDEx
Classifications
CWE-79, T1059.007
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 29, 2026CVE publishedPublication date reported by the CVE source.
  2. Jun 29, 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=0.8.3 <0.13.2
  2. Affected versionversion=9852db2456fdc9d856eb636603a7f608e22e3793 <2817147f5b87ce7186aa604c9ee72499485b8f2f

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Leandro Pereira · MDExversion=0.8.3 <0.13.2; version=9852db2456fdc9d856eb636603a7f608e22e3793 <2817147f5b87ce7186aa604c9ee72499485b8f2f

Published CVSS scores

5.1Leandro PereiraCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:L/VI:L/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

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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