Unauthenticated email relay via unprotected AJAX handler
Published Jul 28, 2026 · Updated Jul 28, 2026
Missing authorization in QuantumCloud WPBot 8.5.9 and earlier allows remote attackers to relay arbitrary email through WordPress. The wpcs_send_email handler accepts attacker-controlled recipients, subjects, and bodies through a public AJAX action and passes them to wp_mail without nonce or capability checks. Any network-reachable site with the plugin active exposes the unauthenticated action; successful abuse sends mail under the site's domain.
Summary
What happened
Missing authorization in QuantumCloud WPBot 8.5.9 and earlier allows remote attackers to relay arbitrary email through WordPress. The wpcs_send_email handler accepts attacker-controlled recipients, subjects, and bodies through a public AJAX action and passes them to wp_mail without nonce or capability checks. Any network-reachable site with the plugin active exposes the unauthenticated action; successful abuse sends mail under the site's domain.
The record
- CVE
- CVE-2026-16774
- Published
- Jul 28, 2026
- Updated
- Jul 28, 2026
- Vendor
- QuantumCloud
- Product
- WPBot
- Classifications
- CWE-862
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jul 28, 2026CVE publishedPublication date reported by the CVE source.
- Jul 28, 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.
- Affected versionversion=0 <=8.5.9
What conditions does exploitation require?
What is affected?
Published CVSS scores
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.
Weakness, pattern, technique
Public exploit references
No public exploit references are available in this record.
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Technologies
Your stack
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Your stack
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