CVE-2026-79310
Received Received - Intake

Server-Side Template Injection in web.py

Publication date: 2026-09-23

Last updated on: 2026-09-23

Assigner: MITRE

Description
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.

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Meta Information

Published
2026-09-23
Last Modified
2026-09-23
Generated
2026-09-23
AI Q&A
2026-09-23
EPSS Evaluated
N/A
NVD
CVE-2026-79310
EUVD
EUVD-2026-85403

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
webpy web.py 0.76

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Exploitability

CWE
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KEV
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CWE ID Description
CWE-UNKNOWN

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Executive Summary

CVE-2026-79310 is a server-side template injection (SSTI) flaw in web.py version 0.76. The vulnerability occurs during template pre-compilation when attacker-controlled code is written to disk before security checks. When these compromised templates are loaded at runtime, they bypass the restricted execution environment, allowing arbitrary Python code and OS command execution on the server.

Detection Guidance

Check for writable template directories in web.py applications using version 0.76. Look for pre-compiled template files in directories accessible to untrusted users. Inspect file permissions and ownership of template directories and generated Python files.

Impact Analysis

This vulnerability allows attackers to execute arbitrary code on the server if they can write to the template directory and trigger template rendering. This could lead to file access, environment variable exposure, and full command execution under the service process identity.

Compliance Impact

This vulnerability could lead to unauthorized code execution on the server, potentially exposing sensitive data. For GDPR, this may result in unauthorized access to personal data, violating principles of data protection and privacy. For HIPAA, it could allow unauthorized access to protected health information, leading to compliance violations and breaches of patient confidentiality.

Mitigation Strategies
  • Avoid using batch pre-compilation of templates in writable directories.
  • Implement stricter file system permissions to prevent untrusted users from writing to template directories.
  • Disable pre-compiled template loading if not required for application functionality.
  • Monitor for unexpected file writes or changes in template directories.

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