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CVE-2026-72701 getgrav CVE debrief

The CVE-2026-72701 vulnerability in Grav CMS before 2.0.16 involves a timing issue in the Utils::verifyNonce() function. This function uses non-constant-time string comparison with the === operator for CSRF nonce validation, allowing attackers to measure response timing differences and recover valid nonce values byte-by-byte through multiple requests. This weakness in CSRF protection can be exploited by attackers to bypass security measures. Administrators and security teams should be aware of this vulnerability and take necessary defensive actions to mitigate potential attacks. The CVE record was published on 2026-08-25T02:16:45.980Z and has not been modified since then.

Vendor
getgrav
Product
grav
CVSS
MEDIUM 6.3
CISA KEV
Not listed in stored evidence
Original CVE published
2026-08-25
Original CVE updated
2026-08-31
Advisory published
2026-08-25
Advisory updated
2026-08-31

Who should care

Administrators and security teams responsible for Grav CMS installations, particularly those using versions before 2.0.16, should be aware of this vulnerability and take necessary defensive actions to mitigate potential attacks. This includes reviewing and enhancing CSRF protection mechanisms, monitoring for unusual request patterns, and applying vendor-provided patches or updates.

Technical summary

The Utils::verifyNonce() function in Grav CMS before 2.0.16 uses non-constant-time string comparison with the === operator for CSRF nonce validation. This allows attackers to measure response timing differences and recover valid nonce values byte-by-byte through multiple requests, weakening CSRF protection below its intended security margin. The vulnerability has a CVSS score of 6.3 and is classified as MEDIUM severity.

Defensive priority

Medium-priority defensive actions are recommended due to the potential for attackers to exploit this vulnerability in Grav CMS versions before 2.0.16.

Recommended defensive actions

  • Inventory and version checks for Grav CMS installations
  • Application of vendor-provided patches or updates
  • Monitoring for unusual request timing patterns
  • Enhancement of CSRF protection mechanisms
  • Review of nonce validation processes
  • Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up.
  • Review compensating controls for exposed systems while remediation is scheduled and verified.

Evidence notes

Evidence from the CVE Program and NVD suggests a timing vulnerability exists in Grav CMS before 2.0.16. The Utils::verifyNonce() function uses non-constant-time string comparison, allowing attackers to recover valid nonce values through response timing differences. Limited source detail is available, so defenders should verify affected scope and vendor guidance while reviewing compensating controls.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-72701 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-72701

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-72701 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-72701

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.