How severe is CVE-2026-44307?

No CVSS score has been assigned to CVE-2026-44307 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2026-44307?

CVE-2026-44307 affects the following packages: mako (PyPI). Ecosystems affected: PyPI.

How do I fix CVE-2026-44307?

Update mako to 1.3.12 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-44307 is resolved across your whole dependency graph.

How do I detect CVE-2026-44307 in my PyPI dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for mako, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2026-44307 if there is no patch (or I can't update yet)?

Resolve every user-supplied path to its canonical form and reject anything that escapes the intended directory, and run the component under an account that has no read or write access outside the directory it legitimately serves.

Is CVE-2026-44307 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-44307 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.

What is the EPSS score for CVE-2026-44307?

CVE-2026-44307 has an EPSS (Exploit Prediction Scoring System) score of 0.7%, placing it in the 55th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2026-44307?

CVE-2026-44307 is classified as Path Traversal (CWE-22). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

When was CVE-2026-44307 published, and has it been updated?

CVE-2026-44307 was published on May 12, 2026 and was last updated on October 28, 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

Not in CISA KEV

CVE-2026-44307 — mako

Fix: sqlalchemy/mako@72e10c5

CVE-2026-44307 is a Path Traversal vulnerability in mako. A fix is available for mako — see the affected versions and patch details below.

Mako: Path traversal via backslash URI on Windows in TemplateLookup

Also known asGHSA-2h4p-vjrc-8xpqPYSEC-2026-2617

Published

May 12, 2026

Updated

Oct 28, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Oct 31, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-44307.

EPSS Exploitation Probability

via FIRST.org ↗

0.7%probability of exploitation in next 30 days

Lower Risk-0.15%

Lower risk than most CVEs55th percentile — riskier than 55% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

Real-World Exposure

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`pip install --upgrade 'mako==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, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update mako to 1.3.12 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-44307 is resolved across your whole dependency graph.
Workarounds
Resolve every user-supplied path to its canonical form and reject anything that escapes the intended directory, and run the component under an account that has no read or write access outside the directory it legitimately serves.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatModerate

This flaw is rated Moderate (CVSS 5.9) because exploitation requires high attack complexity (AC:H) — the path traversal is Windows-specific and depends on attacker-controlled template names being passed to Mako's TemplateLookup. Red Hat products are deployed on Linux where this vulnerability is not exploitable, as…

Workaround published by Red Hat

This vulnerability is specific to Windows systems where backslash characters are interpreted as path separators. Red Hat products running on Linux are not susceptible to this path traversal because Linux does not treat backslash as a directory separator. For any application using Mako on Windows, validate user-controlled template names to reject backslash characters before passing them to TemplateLookup.get_template(). Upgrading to Mako 1.3.12 resolves this issue.

Source: Red Hat security advisory for CVE-2026-44307 (CC BY 4.0)

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

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