How severe is GHSA-2h4p-vjrc-8xpq?

No CVSS score has been assigned to GHSA-2h4p-vjrc-8xpq yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by GHSA-2h4p-vjrc-8xpq?

GHSA-2h4p-vjrc-8xpq affects the following packages: mako (PyPI). Ecosystems affected: PyPI.

How do I fix GHSA-2h4p-vjrc-8xpq?

Update mako to 1.3.12 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-2h4p-vjrc-8xpq is resolved across your whole dependency graph.

How do I detect GHSA-2h4p-vjrc-8xpq in my PyPI dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for mako. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

How do I mitigate GHSA-2h4p-vjrc-8xpq if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

How does O3 Security protect against GHSA-2h4p-vjrc-8xpq?

O3 pinpoints whether GHSA-2h4p-vjrc-8xpq is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Is GHSA-2h4p-vjrc-8xpq actively exploited in the wild?

No public exploit code has been indexed for GHSA-2h4p-vjrc-8xpq yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

When was GHSA-2h4p-vjrc-8xpq published, and has it been updated?

GHSA-2h4p-vjrc-8xpq was published on May 6, 2026 and was last updated on July 13, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐍 PyPI

GHSA-2h4p-vjrc-8xpq

GHSA-2h4p-vjrc-8xpq is a security vulnerability in mako. O3 Security confirms whether GHSA-2h4p-vjrc-8xpq is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.

Mako vulnerable to path traversal via backslash URI on Windows in TemplateLookup

Also known asCVE-2026-44307PYSEC-2026-2617

Published

May 6, 2026

Updated

Jul 13, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Blast Radius

1 pkg affected

🐍mako

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.

Description

Summary

On Windows, a URI using backslash traversal (e.g. \..\..\ secret.txt) bypasses the directory traversal check in Template.__init__ and the posixpath-based normalization in TemplateLookup.get_template(), allowing reads of files outside the configured template directory.

Details

The root cause is a mismatch between posixpath (used for URI normalization in get_template()) and os.path (used for file access via os.path.isfile() and validation via os.path.normpath() in Template.__init__). On Windows, os.path is ntpath, which treats \ as a path separator, while posixpath treats it as a literal character.

The vulnerability chain:

get_template() strips only leading / via re.sub(r"^\/+", "", uri) and normalizes with posixpath — backslash \ is treated as a literal character, so \..\ secret.txt passes through with .. undetected.
Template.__init__() validation uses os.path.normpath() — on Windows this resolves \..\ secret.txt to \secret.txt, which does not start with .., so the startswith("..") check passes.
os.path.isfile() on Windows interprets \ as a path separator, resolving the .. traversal and finding files outside the template directory.

Affected code

mako/lookup.py: TemplateLookup.get_template() uses posixpath.normpath/posixpath.join for path construction but os.path.isfile() for existence check
mako/template.py: Template.__init__() URI validation uses os.path.normpath() which on Windows resolves backslash traversal to a form that passes the startswith("..") guard

Impact

If an application passes user-controlled template names or include paths to TemplateLookup.get_template(), an attacker on Windows may be able to load and disclose readable files outside the configured template directory. The primary impact is local file disclosure. If the targeted file contains Mako/Python template syntax, it may also be parsed and executed as a template.

Remediation

The fix should normalize backslashes to forward slashes early in the URI processing pipeline, before any path operations, to ensure consistent behavior across platforms.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐍PyPI	`mako`	all versions	1.3.12

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for mako. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update mako to 1.3.12 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-2h4p-vjrc-8xpq is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-2h4p-vjrc-8xpq is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to GHSA-2h4p-vjrc-8xpq. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

## Summary On Windows, a URI using backslash traversal (e.g. `\..\..\ secret.txt`) bypasses the directory traversal check in `Template.__init__` and the `posixpath`-based normalization in `TemplateLookup.get_template()`, allowing reads of files outside the configured template directory. ## Details The root cause is a mismatch between `posixpath` (used for URI normalization in `get_template()`) and `os.path` (used for file access via `os.path.isfile()` and validation via `os.path.normpath()` in `Template.__init__`). On Windows, `os.path` is `ntpath`, which treats `\` as a path separator, wh

O3 Security · Impact-Aware SCA

Is GHSA-2h4p-vjrc-8xpq in your dependencies?

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