{"cve":"CVE-2026-55520","nvd":{"published":"2026-08-28T20:18:28.100","modified":"2026-09-09T21:09:13.080","status":"Deferred","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.","cvss_v4":{"vector":"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","score":7.1},"cvss_v3":null,"cwes":["CWE-400","CWE-1333"],"references":["https://github.com/scrapy/protego/commit/785940181659bf440ba82f1da148fade5087e858","https://github.com/scrapy/protego/releases/tag/0.6.2","https://github.com/scrapy/protego/security/advisories/GHSA-wjmf-p669-5m5p"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:50:50.842544443+00:00"},"epss":{"cve":"CVE-2026-55520","score":0.00511,"percentile":0.43577,"date":"2026-11-01"},"kev":null,"osv":[{"id":"GHSA-wjmf-p669-5m5p","url":"https://osv.dev/vulnerability/GHSA-wjmf-p669-5m5p","summary":"Protego has exponential backtracking ReDoS in robots.txt URL wildcard matching","modified":"2026-09-10T12:25:43.026818158Z","packages":[{"ecosystem":"PyPI","name":"protego","purl":"pkg:pypi/protego","ranges":["<0.6.2"],"fixed":["0.6.2"]}]},{"id":"PYSEC-2026-3906","url":"https://osv.dev/vulnerability/PYSEC-2026-3906","summary":"Protego has exponential backtracking ReDoS in robots.txt URL wildcard matching","modified":"2026-09-10T12:15:12.559484951Z","packages":[{"ecosystem":"PyPI","name":"protego","purl":"pkg:pypi/protego","ranges":["<0.6.2"],"fixed":["0.6.2"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}