How severe is CVE-2026-41205?

No CVSS score has been assigned to CVE-2026-41205 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2026-41205?

CVE-2026-41205 affects the following packages: mako (PyPI). Ecosystems affected: PyPI.

How do I fix CVE-2026-41205?

Update mako to 1.3.11 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-41205 is resolved across your whole dependency graph.

How do I detect CVE-2026-41205 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-2026-41205 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-2026-41205 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-41205 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-2026-41205?

CVE-2026-41205 has an EPSS (Exploit Prediction Scoring System) score of 0.4%, placing it in the 30th 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-2026-41205?

CVE-2026-41205 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-2026-41205 published, and has it been updated?

CVE-2026-41205 was published on April 23, 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-2026-41205 — mako

Fix: sqlalchemy/mako@e05ac61

CVE-2026-41205 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 double-slash URI prefix in TemplateLookup

Also known asGHSA-v92g-xgxw-vvmmPYSEC-2026-88

Published

Apr 23, 2026

Updated

Oct 28, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Nov 4, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

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-2026-41205.

EPSS Exploitation Probability

via FIRST.org ↗

0.4%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs30th percentile — riskier than 30% 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

TemplateLookup.get_template() is vulnerable to path traversal when a URI starts with // (e.g., //../../../secret.txt). The root cause is an inconsistency between two slash-stripping implementations:

Template.__init__ strips one leading / using if/slice
TemplateLookup.get_template() strips all leading / using re.sub(r"^\/+", "")

When a URI like //../../../../etc/passwd is passed:

get_template() strips all / → ../../../../etc/passwd → file found via posixpath.join(dir_, u)
Template.__init__ strips one / → /../../../../etc/passwd → normpath → /etc/passwd
/etc/passwd.startswith(..) → False → check bypassed

Impact

Arbitrary file read: any file readable by the process can be returned as rendered template content when an application passes untrusted input directly to TemplateLookup.get_template().

Note: this is exploitable at the library API level. HTTP-based exploitation is mitigated by Python's BaseHTTPRequestHandler which normalizes double-slash prefixes since CPython gh-87389. Applications using other HTTP servers that do not normalize paths may be affected.

Fix

Changed Template.__init__ to use lstrip("/") instead of stripping only a single leading slash, so both code paths handle leading slashes consistently.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐍PyPI	`mako`	all versions	1.3.11`pip install --upgrade 'mako==1.3.11'`

Affected Products

1 product · 1 configurations

Application

makosqlalchemy

< 1.3.11

range

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 1.3.11 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-41205 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

Workaround published by Red Hat

To mitigate this issue, applications utilizing the Mako template library must validate and sanitize all input before passing it to the `TemplateLookup.get_template()` function. Implementing robust input validation routines within applications will prevent specially crafted URIs from traversing outside intended directories and accessing sensitive files.

Source: Red Hat security advisory for CVE-2026-41205 (CC BY 4.0)

Frequently Asked Questions

### Summary `TemplateLookup.get_template()` is vulnerable to path traversal when a URI starts with `//` (e.g., `//../../../secret.txt`). The root cause is an inconsistency between two slash-stripping implementations: - `Template.__init__` strips **one** leading `/` using `if`/slice - `TemplateLookup.get_template()` strips **all** leading `/` using `re.sub(r"^\/+", "")` When a URI like `//../../../../etc/passwd` is passed: 1. `get_template()` strips all `/` → `../../../../etc/passwd` → file found via `posixpath.join(dir_, u)` 2. `Template.__init__` strips one `/` → `/../../../../etc/passwd`

O3 Security · Impact-Aware SCA

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