CSRF nonce recovery via short-circuit comparison
Published Aug 25, 2026 · Updated Aug 27, 2026
Timing side channel in GetGrav Grav before 2.0.16 allows remote attackers to recover CSRF nonces through repeated HTTP requests. Utils::verifyNonce() compares submitted nonces with secret-derived 32-character values using PHP's short-circuiting === operator rather than hash_equals(). Exploitation requires many precisely timed requests and a favorable network position, and a recovered nonce weakens CSRF protection for reachable core or plugin actions.
Summary
What happened
Timing side channel in GetGrav Grav before 2.0.16 allows remote attackers to recover CSRF nonces through repeated HTTP requests. Utils::verifyNonce() compares submitted nonces with secret-derived 32-character values using PHP's short-circuiting === operator rather than hash_equals(). Exploitation requires many precisely timed requests and a favorable network position, and a recovered nonce weakens CSRF protection for reachable core or plugin actions.
The record
- CVE
- CVE-2026-72701
- Published
- Aug 25, 2026
- Updated
- Aug 27, 2026
- Vendor
- GetGrav
- Product
- Grav
- Classifications
- CWE-208, T1190
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Aug 25, 2026CVE publishedPublication date reported by the CVE source.
- Aug 27, 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?
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- Affected versionversion=0 <2.0.16
What conditions does exploitation require?
What is affected?
Published CVSS scores
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Attacks
What attackers are doing with it
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Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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