CVE-2026-10513Public exploitNetwork attack vector

Unauthenticated stored XSS via unescaped author metadata

Published Jun 30, 2026 · Updated Jun 30, 2026

Stored XSS in Matthias Pfefferle Webmention 5.8.0 and earlier allows remote attackers to inject scripts through MF2 author metadata. The REST handler stores parser-derived avatar and URL values, and the edit-comment-form template writes them into HTML value attributes without esc_attr() or esc_url(). No authentication is required to submit the webmention, but script execution requires a moderator or administrator to open the affected comment edit screen.

CVSS severity7.2
High
EPSS probability0.40%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stored XSS in Matthias Pfefferle Webmention 5.8.0 and earlier allows remote attackers to inject scripts through MF2 author metadata. The REST handler stores parser-derived avatar and URL values, and the edit-comment-form template writes them into HTML value attributes without esc_attr() or esc_url(). No authentication is required to submit the webmention, but script execution requires a moderator or administrator to open the affected comment edit screen.

The record

CVE
CVE-2026-10513
Published
Jun 30, 2026
Updated
Jun 30, 2026
Vendor
Matthias Pfefferle
Product
Webmention
Classifications
CWE-79, T1059.007
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 30, 2026CVE publishedPublication date reported by the CVE source.
  2. Jun 30, 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 <=5.8.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Matthias Pfefferle · Webmentionversion=0 <=5.8.0

Published CVSS scores

7.2WordfenceCVSS:3.1/AV:N/AC:L/PR:N/UI:N/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.

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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')
T1059.007JavaScript/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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