Unauthenticated event disclosure via unchecked site selection
Published Apr 16, 2026 · Updated Apr 16, 2026
Authorization bypass in the Joe Dolson calendar plugin before 3.7.7 allows remote attackers to read private WordPress Multisite events. The unauthenticated mc_ajax_mcjs_action endpoint parses the entire args string into key-value pairs, then passes the attacker-controlled site value to switch_to_blog without an authorization check. Multisite exposes cross-site events; on Single Site, the undefined switch_to_blog call raises a fatal PHP error, allowing repeated requests to interrupt worker threads.
Summary
What happened
Authorization bypass in the Joe Dolson calendar plugin before 3.7.7 allows remote attackers to read private WordPress Multisite events. The unauthenticated mc_ajax_mcjs_action endpoint parses the entire args string into key-value pairs, then passes the attacker-controlled site value to switch_to_blog without an authorization check. Multisite exposes cross-site events; on Single Site, the undefined switch_to_blog call raises a fatal PHP error, allowing repeated requests to interrupt worker threads.
The record
- CVE
- CVE-2026-40308
- Published
- Apr 16, 2026
- Updated
- Apr 16, 2026
- Vendor
- Damion Armentrout
- Product
- My Calendar
- Classifications
- CWE-639, T1499.004, T1190
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Apr 16, 2026CVE publishedPublication date reported by the CVE source.
- Apr 16, 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=< 3.7.7
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
- Single Site worker-thread denial-of-service PoCproof of concept · demonstrated
- Multisite cross-site event disclosure PoCproof of concept · demonstrated
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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