CVE-2026-79310: Code Injection
webpy web.py 0.76 is vulnerable to server-side template injection (SSTI). The template engine can be tricked into executing attacker-controlled template code that built-in security checks are designed to reject. When an application precompiles templates from a directory the attacker can write to and later renders them through the precompiled template loader, the sandbox is bypassed and the attacker's code runs, resulting in arbitrary Python code execution and OS command execution on the server.
Affected Software
Event History
Frequently Asked Questions
Which deployments are exposed to this issue?
Applications using web.py 0.76 are exposed when they precompile templates from a directory that an attacker can write to, then render those templates using the precompiled template loader. The described attack depends on that writable-template workflow.
What access does an attacker need to exploit it?
The attacker needs the ability to write a malicious template into the directory used for template precompilation. Rendering the resulting precompiled template triggers attacker-controlled Python code execution.
What is the impact if exploitation succeeds?
Successful exploitation bypasses the template engine's built-in security checks and allows arbitrary Python code execution. This can also lead to operating-system command execution on the server.