CVE-2026-55520

HIGHPre-NVD 7.17.1—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 7.1 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.4%, top 69% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
7.1EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 7.1Exploit: None knownExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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 v3
7.1
EG Score
7.1(medium)
EG Risk
47(Track)
EG Risk 47/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity71% × 45%
Exploitation0% × 40%
Automatability100% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
31%
KEV
Not listed

Published

August 28, 2026

Last Modified

September 9, 2026

Advisory Details (3)

Auto-updated Aug 28, 2026
🔬 Proof of concept available. Patch available. Sources: github, github_commit, github_release.
github Patch Available🟡 PoC Available

Exponential backtracking ReDoS in robots.txt URL wildcard matching · Advisory · scrapy/protego · GitHub

https://github.com/scrapy/protego/security/advisories/GHSA-wjmf-p669-5m5p
github_release Patch Available

Release 0.6.2 (scrapy/protego)

Patch available: scrapy/protego 0.6.2

https://github.com/scrapy/protego/releases/tag/0.6.2
github_commit Patch Available

commit 785940181659 (scrapy/protego)

Patch available: scrapy/protego 0.6.2 (contains commit 785940181659)

https://github.com/scrapy/protego/commit/785940181659bf440ba82f1da148fade5087e858

Vendor Advisories for CVE-2026-55520(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Affected Packages

(4 across 4 ecosystems)
Debian:12(1)
PackageVulnerable rangeFixed inDependents
python-protego0.2.1+dfsg-1 ... 0.6.2+dfsg-1 (7 versions)——
Debian:13(1)
PackageVulnerable rangeFixed inDependents
python-protego0.4.0+dfsg-1, 0.5.0+dfsg-1, 0.6.0+dfsg-1, 0.6.2+dfsg-1——
Debian:14(1)
PackageVulnerable rangeFixed inDependents
python-protego0.4.0+dfsg-1, 0.5.0+dfsg-1, 0.6.0+dfsg-10.6.2+dfsg-1—
PyPI(1)
PackageVulnerable rangeFixed inDependents
protego0.1 ... 0.6.1 (14 versions)0.6.2—

Weakness Classification(2)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 14× in last 7d / 43× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-09-19 16:23 UTCEG score recompute
  2. 2026-09-19 05:31 UTCEG score recompute
  3. 2026-09-18 19:28 UTCEPSS rescore
  4. 2026-09-17 20:50 UTCEG score recompute
  5. 2026-09-17 19:31 UTCEPSS rescore
  6. 2026-09-16 18:58 UTCEG score recompute
  7. 2026-09-16 14:08 UTCEPSS rescore
  8. 2026-09-16 05:49 UTCEG score recompute
  9. 2026-09-16 05:15 UTCEPSS rescore
  10. 2026-09-15 08:05 UTCEG score recompute
  11. 2026-09-15 03:11 UTCEPSS rescore
  12. 2026-09-13 23:04 UTCEG score recompute
  13. 2026-09-13 16:47 UTCEPSS rescore
  14. 2026-09-13 01:20 UTCEG score recompute
  15. 2026-09-11 16:43 UTCEG score recompute
  16. 2026-09-11 14:53 UTCEPSS rescore
  17. 2026-09-10 18:57 UTCEG score recompute
  18. 2026-09-10 09:35 UTCEPSS rescore
  19. 2026-09-09 00:27 UTCEG score recompute
  20. 2026-09-08 22:01 UTCEPSS rescore
  21. 2026-09-08 02:01 UTCEG score recompute
  22. 2026-09-07 16:01 UTCEPSS rescore
  23. 2026-09-06 17:21 UTCEG score recompute
  24. 2026-09-06 13:47 UTCEPSS rescore
  25. 2026-09-05 19:35 UTCEG score recompute
Show 18 more
  1. 2026-09-04 21:50 UTCEG score recompute
  2. 2026-09-04 10:58 UTCEG score recompute
  3. 2026-09-04 05:06 UTCEPSS rescore
  4. 2026-09-02 15:10 UTCEG score recompute
  5. 2026-09-02 14:12 UTCEPSS rescore
  6. 2026-09-01 17:17 UTCEG score recompute
  7. 2026-09-01 13:54 UTCEPSS rescore
  8. 2026-09-01 06:25 UTCEG score recompute
  9. 2026-09-01 04:40 UTCEPSS rescore
  10. 2026-08-31 19:31 UTCEG score recompute
  11. 2026-08-31 18:57 UTCEG score recompute
  12. 2026-08-31 02:52 UTCEG score recompute
  13. 2026-08-30 19:17 UTCEPSS rescore
  14. 2026-08-30 05:07 UTCEG score recompute
  15. 2026-08-30 01:22 UTCEPSS rescore
  16. 2026-08-28 20:24 UTCEG score recompute▲ 7.10
  17. 2026-08-28 20:24 UTCNVD updateCVSS v3 → 7.1 · CVSS v4 → 7.1
  18. 2026-08-28 19:10 UTCEG score recompute

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-55520?
CVE-2026-55520 is a high vulnerability published on August 28, 2026. Protego is a pure-Python robots.txt parser with support for modern conventions. Prior to 0.6.2, protego.urlpattern.URLPattern.preparepatternforregex translates every asterisk in an Allow or Disallow directive into a lazy regular-expression wildcard, so a directive containing many asterisks creates…
When was CVE-2026-55520 disclosed?
CVE-2026-55520 was first published in the National Vulnerability Database on August 28, 2026, with the most recent update on September 9, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-55520 actively exploited?
CVE-2026-55520 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 69.3% of all scored CVEs.
What is the CVSS score of CVE-2026-55520?
CVE-2026-55520 has a CVSS v3 base score of 7.1 (NVD).
How do I remediate CVE-2026-55520?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-55520, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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