CVE-2026-55520Protego: Exponential backtracking ReDoS in robots.txt URL wildcard matching
Updated under an hour ago ()
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No exploitation reported and no EPSS estimate yet.
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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
- 7.1 HIGH (v4.0, CNA)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
- Weakness (CWE)
- CWE-400, CWE-1333
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- GitHub_M
- NVD analysis
- Deferred
- Record last updated
- Aug 31, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
scrapy protego scrapy:protego (from the name) | before 0.6.2 | CNA record |
References
- https://github.com/scrapy/protego/security/advisories/GHSA-wjmf-p669-5m5px-refsource-confirm
- https://github.com/scrapy/protego/commit/785940181659bf440ba82f1da148fade5087e858x-refsource-misc
- https://github.com/scrapy/protego/releases/tag/0.6.2x-refsource-misc
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.