CVE-2026-72701 Grav CMS before 2.0.16 Timing Attack via verifyNonce
Attackers can bypass CSRF protection in Grav CMS by exploiting a timing side-channel in nonce validation to recover valid tokens.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-72701?
CVE-2026-72701 is a medium-severity vulnerability in getgrav grav, published on 25 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Grav CMS before 2.0.16 contains a timing vulnerability in Utils::verifyNonce() that uses non-constant-time string comparison with the === operator instead of hash_equals() for CSRF nonce validation. Attackers can measure response timing differences to recover valid nonce values byte-by-byte through multiple requests, weakening CSRF protection below its intended security margin.
Weakness: CWE-208
Which versions are affected by CVE-2026-72701?
2 open source packages ship an affected version, including getgrav/grav.
| Package | Affected | Fixed in |
|---|---|---|
getgrav/grav Packagist | All versions | 2.0.16 |
getgrav/grav Packagist | All versions | 2.0.16 |
How do I fix CVE-2026-72701?
Upgrade getgrav/grav to 2.0.16 or later.
Is CVE-2026-72701 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-72701 exists.
Sources
Also known as GHSA-38p6-h87p-r4cg.