CVE-2026-52778 YesWiki has Unsafe eval() in Formula Calculator - Remote Code Execution (RCE) & Denial of Service (DoS)
Attackers can execute arbitrary PHP code or crash the server via unsafe eval() in YesWiki's formula calculator.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-52778?
CVE-2026-52778 is a critical code injection vulnerability in yeswiki, published on 8 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
YesWiki is a wiki system written in PHP. Prior to version 4.6.6, an unsafe execution vulnerability exists in the Bazar form field calculator (CalcField.php) of YesWiki. The application attempts to sanitize user-defined mathematical formulas using a complex recursive regular expression before passing them to the PHP eval() function. This implementation is inherently flawed: it is vulnerable to Regular Expression Denial of Service (ReDoS / Stack Overflow) which can crash the server, and it creates a high-risk architecture where any logic bypass directly results in arbitrary PHP code execution. Version 4.6.6 patches the issue.
Which versions are affected by CVE-2026-52778?
2 open source packages ship an affected version, including yeswiki/yeswiki.
| Package | Affected | Fixed in |
|---|---|---|
yeswiki/yeswiki Packagist | All versions | 4.6.6 |
yeswiki/yeswiki Packagist | All versions | 4.6.6 |
How do I fix CVE-2026-52778?
Upgrade yeswiki/yeswiki to 4.6.6 or later.
Upgrade, and never evaluate templates, expressions or code built from user input. More about Code injection.
Is CVE-2026-52778 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-52778 exists.
Sources
Also known as GHSA-px5m-h76g-p7p8.