{"id":"DEBIAN-CVE-2026-55520","details":"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.","modified":"2026-09-29T13:04:11.499799087Z","published":"2026-08-28T20:18:28.100Z","upstream":["CVE-2026-55520"],"references":[{"type":"ADVISORY","url":"https://security-tracker.debian.org/tracker/CVE-2026-55520"}],"affected":[{"package":{"name":"python-protego","ecosystem":"Debian:12","purl":"pkg:deb/debian/python-protego?arch=source&distro=bookworm"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.2.1+dfsg-1","0.3.0+dfsg-1","0.3.1+dfsg-1","0.4.0+dfsg-1","0.5.0+dfsg-1","0.6.0+dfsg-1","0.6.2+dfsg-1","0.7.0+dfsg-1"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2026-55520.json"}},{"package":{"name":"python-protego","ecosystem":"Debian:13","purl":"pkg:deb/debian/python-protego?arch=source&distro=trixie"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.4.0+dfsg-1","0.5.0+dfsg-1","0.6.0+dfsg-1","0.6.2+dfsg-1","0.7.0+dfsg-1"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2026-55520.json"}},{"package":{"name":"python-protego","ecosystem":"Debian:14","purl":"pkg:deb/debian/python-protego?arch=source&distro=forky"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.6.2+dfsg-1"}]}],"versions":["0.4.0+dfsg-1","0.5.0+dfsg-1","0.6.0+dfsg-1"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2026-55520.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X"}]}