CVE-2023-34253 Grav vulnerable to Server-side Template Injection (SSTI) via Denylist Bypass
A low-privileged attacker with admin panel access can achieve remote code execution by bypassing the template injection denylist in Grav CMS.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2023-34253?
CVE-2023-34253 is a high-severity code injection vulnerability in Getgrav Grav, published on 14 Jun 2023. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
Grav is a flat-file content management system. Prior to version 1.7.42, the denylist introduced in commit 9d6a2d to prevent dangerous functions from being executed via injection of malicious templates was insufficient and could be easily subverted in multiple ways -- (1) using unsafe functions that are not banned, (2) using capitalised callable names, and (3) using fully-qualified names for referencing callables. Consequently, a low privileged attacker with login access to Grav Admin panel and page creation/update permissions is able to inject malicious templates to obtain remote code execution. A patch in version 1.7.42 improves the denylist.
Which versions are affected by CVE-2023-34253?
2 open source packages ship an affected version, including getgrav/grav. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
getgrav/grav Packagist | All versions | 1.7.42 |
getgrav/grav Packagist | All versions | 1.7.42 |
Products include Getgrav Grav.
How do I fix CVE-2023-34253?
Upgrade getgrav/grav to 1.7.42 or later.
Upgrade, and never evaluate templates, expressions or code built from user input. More about Code injection.
Is CVE-2023-34253 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2023-34253 exists.
Other vulnerabilities in Getgrav Grav
- CVE-2023-34251 Grav Server Side Template Injection vulnerability
- CVE-2025-46199 Cross-site scripting in n/a
- CVE-2021-47812 GravCMS 1.10.7 - Arbitrary YAML Write/Update (Unauthenticated) (2)
- CVE-2025-66844 Grav may be vulnerable to SSRF attack via Twig Templates
- CVE-2022-2073 Code Injection in getgrav/grav
Sources
Also known as GHSA-j3v8-v77f-fvgm.