CVE-2026-64638Public exploitNetwork attack vectorHinoki check available

Pre-auth script execution via login parser disagreement

Published Aug 7, 2026 · Updated Aug 7, 2026

Reflected XSS in the WordPress login screen allows remote attackers to run script in the site's origin through a failed login. The invalid-username error inserts the non-strictly sanitized username into HTML; a space after '<' survives PHP strip_tags(), then WordPress KSES reparses it as allowed DOM nodes that user-profile.js automatically activates. The pre-authentication script execution requires a victim to visit an attacker-controlled page; reaching PHP execution further requires an authenticated administrator session and the documented application-password and plugin-upload chain.

CVSS severity8.9
High
EPSS probability31.20%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
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Summary

What happened

Reflected XSS in the WordPress login screen allows remote attackers to run script in the site's origin through a failed login. The invalid-username error inserts the non-strictly sanitized username into HTML; a space after '<' survives PHP strip_tags(), then WordPress KSES reparses it as allowed DOM nodes that user-profile.js automatically activates. The pre-authentication script execution requires a victim to visit an attacker-controlled page; reaching PHP execution further requires an authenticated administrator session and the documented application-password and plugin-upload chain.

The record

CVE
CVE-2026-64638
Published
Aug 7, 2026
Updated
Aug 7, 2026
Vendor
WordPress.org
Product
WordPress
Classifications
CWE-79, T1189
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 7, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 7, 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?

Affected versions are unavailable in this record. Check the vendor advisory for version and patch details.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

WordPress.org · WordPressAffected versions are unavailable in this record.

Published CVSS scores

8.9HackerOneCVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H

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')
T1189Drive-by Compromise

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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