# CVE-2026-55520: python-protego: Protego is a pure-Python robots.txt parser with support for modern conventions

CVE-2026-55520 is fixed in python-protego on 1 platform by DEBIAN-CVE-2026-55520 (version 0.6.2+dfsg-1), released June 28, 2026. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2026-55520
- Priority: Routine
- CVSS: n/a
- EPSS: 0.0051
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Aug 28, 2026

## Description

Protego is a pure-Python robots.txt parser with support for modern conventions. Prior to 0.6.2, protego._urlpattern._URLPattern._prepare_pattern_for_regex translates every asterisk in an Allow or Disallow directive into a lazy regular-expression wildcard, so a directive containing many asterisks creates exponential backtracking. After protego.Protego.parse processes a crafted robots.txt file, protego.Protego.can_fetch can spend an attacker-controlled period matching a near-miss URL and deny service to the crawler. The vulnerable path is src/protego/_urlpattern.py in the _URLPattern match logic. This issue is fixed in version 0.6.2.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | python-protego Debian 14 | 0.6.2+dfsg-1 | [DEBIAN-CVE-2026-55520](https://patchblox.com/security/data/fix/linux/debian-cve-2026-55520.md) | Jun 28, 2026 |

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Data as of 2026-11-10T07:50:38Z 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 Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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