Privileged actions via tokenless state-changing requests
Published Mar 9, 2026 · Updated Mar 9, 2026
Cross-site request forgery in InstantCMS before 2.18.1 allows remote attackers to perform privileged actions through a victim's browser. The friend-request, post-trash, scheduler-run, and moderator-add endpoints accept state-changing requests without validating a CSRF token. A logged-in user with the required permission must load attacker-controlled rich content; resulting actions can accept friendships, trash posts, run scheduled tasks, or grant moderator rights.
Summary
What happened
Cross-site request forgery in InstantCMS before 2.18.1 allows remote attackers to perform privileged actions through a victim's browser. The friend-request, post-trash, scheduler-run, and moderator-add endpoints accept state-changing requests without validating a CSRF token. A logged-in user with the required permission must load attacker-controlled rich content; resulting actions can accept friendships, trash posts, run scheduled tasks, or grant moderator rights.
The record
- CVE
- CVE-2026-28281
- Published
- Mar 9, 2026
- Updated
- Mar 9, 2026
- Vendor
- InstantCMS Team
- Product
- InstantCMS
- Classifications
- CWE-352, T1189
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Mar 9, 2026CVE publishedPublication date reported by the CVE source.
- Mar 9, 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=< 2.18.1
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.
Public exploit references
- GHSA endpoint request demonstrationsfunctional · demonstrated
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Technologies
Your stack
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Your stack
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