# CVE-2026-41205: Mako: Path traversal via double-slash URI prefix in TemplateLookup

CVE-2026-41205 is fixed in 3 products on 1 platform, first by python3-mako 1.3.10-3ubuntu0.1, released April 23, 2026. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2026-41205
- Priority: High
- CVSS: n/a (Important)
- EPSS: 0.0036
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Apr 23, 2026
- Weakness: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-41205

## Description

Mako is a template library written in Python. Prior to 1.3.11, 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. Any file readable by the process can be returned as rendered template content when an application passes untrusted input directly to TemplateLookup.get_template(). This vulnerability is fixed in 1.3.11.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | python-mako Ubuntu 18.04.6 LTS (bionic) | 1.0.7+ds1-1ubuntu0.2+esm1 | [python-mako 1.0.7+ds1-1ubuntu0.2+esm1](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-python-mako-1.0.7-ds1-1ubuntu0.2-esm1.md) | May 15, 2026 |
| Linux | python-mako Ubuntu 20.04 LTS (focal) | 1.1.0+ds1-1ubuntu2.1+esm1 | [python-mako 1.1.0+ds1-1ubuntu2.1+esm1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-python-mako-1.1.0-ds1-1ubuntu2.1-esm1.md) | May 15, 2026 |
| Linux | python-mako-doc amzn 2023 | 1.1.4-3.amzn2023.0.4 | [ALAS2023-2026-1846](https://patchblox.com/security/data/fix/linux/alas2023-2026-1846.md) | Jun 22, 2026 |
| Linux | python3-mako Ubuntu 18.04.6 LTS (bionic) | 1.0.7+ds1-1ubuntu0.2+esm1 | [python3-mako 1.0.7+ds1-1ubuntu0.2+esm1](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-python3-mako-1.0.7-ds1-1ubuntu0.2-esm1.md) | May 15, 2026 |
| Linux | python3-mako Ubuntu 20.04 LTS (focal) | 1.1.0+ds1-1ubuntu2.1+esm1 | [python3-mako 1.1.0+ds1-1ubuntu2.1+esm1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-python3-mako-1.1.0-ds1-1ubuntu2.1-esm1.md) | May 15, 2026 |
| Linux | python3-mako Ubuntu 22.04.1 LTS (jammy) | 1.1.3+ds1-2ubuntu0.2 | [python3-mako 1.1.3+ds1-2ubuntu0.2](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-python3-mako-1.1.3-ds1-2ubuntu0.2.md) | May 15, 2026 |
| Linux | python3-mako Ubuntu 24.04.5 LTS (noble) | 1.3.2-1ubuntu0.1 | [python3-mako 1.3.2-1ubuntu0.1](https://patchblox.com/security/data/fix/linux/ubuntu-noble-python3-mako-1.3.2-1ubuntu0.1.md) | May 15, 2026 |
| Linux | python3-mako Ubuntu 25.10 (questing) | 1.3.9-1ubuntu0.1 | [python3-mako 1.3.9-1ubuntu0.1](https://patchblox.com/security/data/fix/linux/ubuntu-questing-python3-mako-1.3.9-1ubuntu0.1.md) | May 15, 2026 |
| Linux | python3-mako Ubuntu 26.04.1 LTS (resolute) | 1.3.10-3ubuntu0.1 | [python3-mako 1.3.10-3ubuntu0.1](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-python3-mako-1.3.10-3ubuntu0.1.md) | Apr 23, 2026 |
| Linux | python3-mako amzn 2023 | 1.1.4-3.amzn2023.0.4 | [ALAS2023-2026-1846](https://patchblox.com/security/data/fix/linux/alas2023-2026-1846.md) | Jun 22, 2026 |

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Data as of 2026-11-08T06:59:42Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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