CVE-2026-42613: Grav Vulnerable to Privilege Escalation via Missing Server-Side Validation of groups/access

Should you act?

Critical and remotely reachable

No known exploitation yet, but it is network-reachable without credentials. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

• Not in CISA KEV, but CISA’s SSVC assessment records a public proof-of-concept, so attack code exists.
• EPSS 0.6%, percentile 46: FIRST’s model estimates a 0.6% chance of exploitation activity in the next 30 days, higher than 46% of all scored CVEs (low). EPSS is a probability, not a verdict.
• Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
• Only applies if your dependency tree includes getgrav/grav (Composer (PHP)) < 2.0.0-beta.2, fixed in 2.0.0-beta.2. Check your lockfile, including transitive dependencies.

What it is

Grav is a file-based Web platform. Prior to 2.0.0-beta.2, the Login::register() method in the Login plugin accepts attacker-controlled groups and access fields from the registration POST data without server-side validation. When registration is enabled and groups or access are included in the configured allowed fields list, an unauthenticated user can self-register with admin.super privileges by injecting these fields into the registration request. This vulnerability is fixed in 2.0.0-beta.2.

From the GitHub advisory

Bug Report: Registration Privilege Escalation via Missing Server-Side Validation of groups/access

Summary

The Login::register() method in the Login plugin accepts attacker-controlled groups and access fields from the registration POST data without server-side validation. When registration is enabled and groups or access are included in the configured allowed fields list, an unauthenticated user can self-register with admin.super privileges by injecting these fields into the registration request.

This is a missing server-side validation issue — the only defense is a config-level fields allowlist, which is an admin-facing setting, not a hardcoded security boundary.

Affected Component

Weakness type: CWE-20, CWE-862.

Product: getgrav/grav (Composer (PHP)) · Assigned by: GitHub_M · Published: 2026-05-11

Affected and fixed versions

Severity scores

• Attack vector: network (remotely reachable)
• Attack complexity: low
• Privileges required: none (no login)
• User interaction: none
• Scope: unchanged

CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.

Exploitation and urgency

• CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
• CISA SSVC assessment: exploitation poc, automatable yes, technical impact total.
• FIRST EPSS (model of 2026-10-21): 0.56% probability of exploitation activity in the next 30 days; percentile 46.

Timeline

• 2026-05-05 — GitHub-reviewed advisory GHSA-pxm6-mhxr-q4mj published (critical)
• 2026-05-11 — CVE record published by GitHub_M
• 2026-05-12 — CVE record last updated

Sources and references

Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.

Vulnerability records

1. GitHub Advisory GHSA-pxm6-mhxr-q4mj github.com
2. CVE.org record CVE-2026-42613 cve.org
3. NVD entry CVE-2026-42613 nvd.nist.gov

Other references from the CVE record and advisory

1. github.com github.com
2. github.com github.com
3. github.com github.com

Critical Composer (PHP) advisories · Today’s Security Digest