CVE-2021-29440 Twig allowing dangerous PHP functions by default

What is CVE-2021-29440?

CVE-2021-29440 is a high-severity vulnerability in Getgrav Grav, published on 13 Apr 2021.

Official description

Grav is a file based Web-platform. Twig processing of static pages can be enabled in the front matter by any administrative user allowed to create or edit pages. As the Twig processor runs unsandboxed, this behavior can be used to gain arbitrary code execution and elevate privileges on the instance. The issue was addressed in version 1.7.11.

Weakness: CWE-94

Which versions are affected by CVE-2021-29440?

2 open source packages ship an affected version, including getgrav/grav. It affects 1 product.

Products include Getgrav Grav.

How do I fix CVE-2021-29440?

Upgrade getgrav/grav to 1.7.11 or later.

Is CVE-2021-29440 being exploited?

There is no known exploitation of CVE-2021-29440 in the wild and no public exploit code.

Public exploit code: 1 Exploit-DB entry and 1 proofs of concept on GitHub.

Other vulnerabilities in Getgrav Grav

• CVE-2023-34251 Grav Server Side Template Injection vulnerability Critical 10.0
• CVE-2025-46199 Cross-site scripting in n/a Critical 9.8
• CVE-2021-47812 GravCMS 1.10.7 - Arbitrary YAML Write/Update (Unauthenticated) (2) Critical 9.3
• CVE-2025-66844 Grav may be vulnerable to SSRF attack via Twig Templates Critical 9.1
• CVE-2022-2073 Code Injection in getgrav/grav Critical 9.1

All Getgrav Grav vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as GHSA-g8r4-p96j-xfxc.