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Low, CVSS 3.7amended

Grav: Non constant time nonce comparison in Utils::verifyNonce() used for CSRF protection

CVE-2026-72701GHSA-38p6-h87p-r4cg

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (getgrav/grav 2.0.16), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS
3.7 · CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N
EPSS
  • CVE-2026-72701: 0.22% estimated exploitation activity in the next 30 days; percentile 12.11 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

Summary `Grav\Common\Utils::verifyNonce()`, the core function Grav and its plugins use to validate CSRF nonces, compares the submitted nonce to the expected value with PHP's `===` operator instead of `hash_equals()`. `===` on strings short circuits at the first differing byte, so the comparison time leaks how many leading bytes of a guess are correct. This is CWE-208, Observable Timing Discrepancy. The codebase already knows to avoid this pattern. `hash_equals()` is used for the equivalent purpose in four other places I found: `system/src/Grav/Common/Session.php`, `system/src/Grav/Framework/Cache/Adapter/FileCache.php`, `system/src/Grav/Common/Scheduler/Scheduler.php` (the webhook token check), and `system/src/Grav/Common/Scheduler/JobQueue.php`. `Utils::verifyNonce()` is the one place I found that still uses a plain equality check for a secret comparison.

Affected product and version Product: Grav CMS, getgrav/grav Confirmed present in: 2.0.15, commit…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 4 · amended ·

    Amended from osv record GHSA-38p6-h87p-r4cg

  2. Revision 3 · amended ·

    Amended from ghsa record GHSA-38p6-h87p-r4cg

  3. Revision 2 · amended ·

    Amended from ghsa record GHSA-38p6-h87p-r4cg

  4. Revision 1 · created ·

    Published from osv record GHSA-38p6-h87p-r4cg

Agent brief

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# Patch Next advisory brief: CVE-2026-72701

Advisory: Grav: Non constant time nonce comparison in Utils::verifyNonce() used for CSRF protection
IDs: CVE-2026-72701, GHSA-38p6-h87p-r4cg
Record: https://patchnext.com/advisories/cve-2026-72701 (revision 4, source checked 27 Oct 2026, 06:25 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Low (CVSS 3.7)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: getgrav/grav 2.0.16. A vendor fix does not mean a deployment is fixed.

## Affected components
- Packagist getgrav/grav: affected < 2.0.16; fixed in 2.0.16

## Suggested inspection (read-only)
- Packagist getgrav/grav: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on getgrav/grav.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-38p6-h87p-r4cg (OSV record GHSA-38p6-h87p-r4cg lists affected ranges: Packagist getgrav/grav >=0 <2.0.16 (fixed))
- Verified: https://github.com/advisories/GHSA-38p6-h87p-r4cg (GitHub-reviewed advisory GHSA-38p6-h87p-r4cg lists affected ranges: Packagist getgrav/grav >=0 <=2.0.15)

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