CVE-2026-55520

Name	CVE-2026-55520
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.
Source	CVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
python-protego (PTS)	bookworm	0.2.1+dfsg-1	vulnerable
	trixie	0.4.0+dfsg-1	vulnerable
	forky, sid	0.6.2+dfsg-1	fixed

The information below is based on the following data on fixed versions.

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
python-protego	source	(unstable)	0.6.2+dfsg-1

Notes

[trixie] - python-protego <no-dsa> (Minor issue)
[bookworm] - python-protego <postponed> (Minor issue)
[bullseye] - python-protego <postponed> (Minor issue)
https://github.com/scrapy/protego/security/advisories/GHSA-wjmf-p669-5m5p
Fixed by: https://github.com/scrapy/protego/commit/785940181659bf440ba82f1da148fade5087e858 (0.6.2)