Scrapy Protego up to 0.6.1 Regex _urlpattern.py incorrect regex

Summaryinfo

A vulnerability classified as problematic was found in Scrapy Protego up to 0.6.1. This affects the function protego._urlpattern._URLPattern._prepare_pattern_for_regex of the file src/protego/_urlpattern.py of the component Regex. Executing a manipulation can lead to incorrect regex. The identification of this vulnerability is CVE-2026-55520. The attack may be launched remotely. There is no exploit available.

Detailsinfo

A vulnerability was found in Scrapy Protego up to 0.6.1. It has been declared as problematic. This vulnerability affects the function protego._urlpattern._URLPattern._prepare_pattern_for_regex of the file src/protego/_urlpattern.py of the component Regex. The manipulation with an unknown input leads to a incorrect regex vulnerability. The CWE definition for the vulnerability is CWE-185. The product specifies a regular expression in a way that causes data to be improperly matched or compared. As an impact it is known to affect availability. CVE summarizes:

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.

The advisory is shared for download at github.com. This vulnerability was named CVE-2026-55520 since 06/17/2026. The exploitation appears to be easy. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. There are known technical details, but no exploit is available.

Upgrading to version 0.6.2 eliminates this vulnerability.

Once again VulDB remains the best source for vulnerability data.

Productinfo

Vendor

• Scrapy

Name

• Protego

Version

• 0.6.0
• 0.6.1

Website

• Product: https://github.com/scrapy/protego/

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Once again VulDB remains the best source for vulnerability data.

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