CVE-2026-55520

HIGHPre-NVD 7.17.1
EchelonGraph scoreMEDIUM confidence

“—” beside the score: it is equal to the CVSS score beside it.

This high-severity CVE scores 7.1 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.5% (41st percentile of EPSS-scored CVEs). No GitHub Security Advisory CVSS is on record for this CVE.

Triggered by: Headline CVSS from a secondary CVSS source
Sources: EPSS, a secondary CVSS source
7.1EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines at low or medium mission impact and sooner than that at high (the SSVC decision on this page).
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.5%CVSS: 7.1Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

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
7.1HIGHmedium confidence
EG Risk
47
EG Risk 47/100

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 (value × EchelonGraph’s weight)
Severity71% × 45%
The EG Score, 7.1 of 10.
Exploitation0.5% × 40%
FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.
Automatability100% × 15%
CISA's SSVC Automatable value: yes (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Attend at high (mission-essential systems).
Exploitation none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.
Action: A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
EPSS PROB
0.5%
EPSS %ILE
41st
KEV
Not listed

SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Attend at high (mission-essential systems).

A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.

Exploitation none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table

BOD 26-04 (CISA's remediation timeline, Table 1)14 days if the affected system is publicly exposed; 60 days if it is not.

In CISA KEV no (CISA's KEV catalog) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it

Published

August 28, 2026

Last Modified

September 9, 2026

Advisory Details (3)

Auto-updated Aug 28, 2026
Patch available. Sources: github, github_commit, github_release.
GitHub advisoryMentions a patch (unverified)

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 rangeFix by version rangeDependents
python-protego0.2.1+dfsg-1 ... 0.7.0+dfsg-1 (8 versions)
  • every version on: no fix on record
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
python-protego0.4.0+dfsg-1, 0.5.0+dfsg-1, 0.6.0+dfsg-1, 0.6.2+dfsg-1, 0.7.0+dfsg-1
  • every version on: no fix on record
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
python-protego0.4.0+dfsg-1, 0.5.0+dfsg-1, 0.6.0+dfsg-1
  • every version up to 0.6.2+dfsg-1: fixed in 0.6.2+dfsg-1
—
PyPI(1)
PackageVulnerable rangeFix by version rangeDependents
protego0.1 ... 0.6.1 (14 versions)
  • every version up to 0.6.2: fixed in 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 / 57× in last 30d)

Each row is a time one of our pipelines fetched, updated or re-scored this CVE. 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. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.

  1. 2026-10-13 16:34 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  2. 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  3. 2026-10-12 15:55 UTCEG score recompute
  4. 2026-10-11 19:39 UTCEG score recompute
  5. 2026-10-11 16:54 UTCEG score recompute
  6. 2026-10-11 14:17 UTCEG score recompute
  7. 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  8. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  9. 2026-10-10 00:49 UTCEG score recompute
  10. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  11. 2026-10-09 02:37 UTCEG score recompute
  12. 2026-10-08 17:12 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  13. 2026-10-08 00:50 UTCEG score recompute
  14. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  15. 2026-10-06 22:37 UTCEG score recompute
  16. 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  17. 2026-10-06 00:47 UTCEG score recompute
  18. 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  19. 2026-10-05 01:20 UTCEG score recompute
  20. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  21. 2026-10-03 16:02 UTCEG score recompute
  22. 2026-10-03 14:26 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  23. 2026-10-03 04:27 UTCEG score recompute
  24. 2026-10-02 17:56 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  25. 2026-10-02 06:42 UTCEG score recompute
Show 64 more
  1. 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  2. 2026-09-30 19:48 UTCEG score recompute
  3. 2026-09-30 15:03 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  4. 2026-09-30 03:49 UTCEG score recompute
  5. 2026-09-29 15:22 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  6. 2026-09-29 01:41 UTCEG score recompute
  7. 2026-09-28 14:49 UTCEG score recompute
  8. 2026-09-28 13:51 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  9. 2026-09-27 17:04 UTCEG score recompute
  10. 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  11. 2026-09-26 19:19 UTCEG score recompute
  12. 2026-09-26 15:59 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  13. 2026-09-26 08:04 UTCEG score recompute
  14. 2026-09-24 18:42 UTCEG score recompute
  15. 2026-09-24 14:04 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  16. 2026-09-23 19:52 UTCEG score recompute
  17. 2026-09-23 17:54 UTCEPSS rescoreEPSS 0.4% · 30th percentile
  18. 2026-09-22 20:35 UTCEG score recompute
  19. 2026-09-21 22:48 UTCEG score recompute
  20. 2026-09-21 01:02 UTCEG score recompute
  21. 2026-09-20 20:16 UTCEPSS rescoreEPSS 0.4% · 30th percentile
  22. 2026-09-19 16:23 UTCEG score recompute
  23. 2026-09-19 05:31 UTCEG score recompute
  24. 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.4% · 30th percentile
  25. 2026-09-17 20:50 UTCEG score recompute
  26. 2026-09-17 19:31 UTCEPSS rescoreEPSS 0.4% · 30th percentile
  27. 2026-09-16 18:58 UTCEG score recompute
  28. 2026-09-16 14:08 UTCEPSS rescoreEPSS 0.4% · 30th percentile
  29. 2026-09-16 05:49 UTCEG score recompute
  30. 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.4% · 30th percentile
  31. 2026-09-15 08:05 UTCEG score recompute
  32. 2026-09-15 03:11 UTCEPSS rescoreEPSS 0.4% · 30th percentile
  33. 2026-09-13 23:04 UTCEG score recompute
  34. 2026-09-13 16:47 UTCEPSS rescoreEPSS 0.4% · 30th percentile
  35. 2026-09-13 01:20 UTCEG score recompute
  36. 2026-09-11 16:43 UTCEG score recompute
  37. 2026-09-11 14:53 UTCEPSS rescoreEPSS 0.4% · 30th percentile
  38. 2026-09-10 18:57 UTCEG score recompute
  39. 2026-09-10 09:35 UTCEPSS rescoreEPSS 0.4% · 30th percentile
  40. 2026-09-09 00:27 UTCEG score recompute
  41. 2026-09-08 22:01 UTCEPSS rescoreEPSS 0.4% · 30th percentile
  42. 2026-09-08 02:01 UTCEG score recompute
  43. 2026-09-07 16:01 UTCEPSS rescoreEPSS 0.4% · 29th percentile
  44. 2026-09-06 17:21 UTCEG score recompute
  45. 2026-09-06 13:47 UTCEPSS rescoreEPSS 0.4% · 29th percentile
  46. 2026-09-05 19:35 UTCEG score recompute
  47. 2026-09-04 21:50 UTCEG score recompute
  48. 2026-09-04 10:58 UTCEG score recompute
  49. 2026-09-04 05:06 UTCEPSS rescoreEPSS 0.4% · 29th percentile
  50. 2026-09-02 15:10 UTCEG score recompute
  51. 2026-09-02 14:12 UTCEPSS rescoreEPSS 0.4% · 29th percentile
  52. 2026-09-01 17:17 UTCEG score recompute
  53. 2026-09-01 13:54 UTCEPSS rescoreEPSS 0.4% · 29th percentile
  54. 2026-09-01 06:25 UTCEG score recompute
  55. 2026-09-01 04:40 UTCEPSS rescoreEPSS 0.4% · 29th percentile
  56. 2026-08-31 19:31 UTCEG score recompute
  57. 2026-08-31 18:57 UTCEG score recompute
  58. 2026-08-31 02:52 UTCEG score recompute
  59. 2026-08-30 19:17 UTCEPSS rescoreEPSS 0.4% · 29th percentile
  60. 2026-08-30 05:07 UTCEG score recompute
  61. 2026-08-30 01:22 UTCEPSS rescoreEPSS 0.4% · 29th percentile
  62. 2026-08-28 20:24 UTCEG score recomputeFirst assessed: 7.1 HIGH
  63. 2026-08-28 20:24 UTCNVD updateCVSS v3 → 7.1 · CVSS v4 → 7.1
  64. 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-severity vulnerability; its CVE record was 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 the CVE record for CVE-2026-55520 published?
The CVE record for CVE-2026-55520 was published on August 28, 2026. That is the record's publication date; the vulnerability itself may have been made public earlier. EchelonGraph's copy of the record carries a last-modified date of September 9, 2026; the record at its source may have been updated since.
Is CVE-2026-55520 actively exploited?
CVE-2026-55520 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.5% probability of exploitation in the next 30 days (41st percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-55520?
CVE-2026-55520 has a CVSS base score of 7.1 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-55520?
A fix for CVE-2026-55520 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-55520 are linked in the Vendor Advisories panel on this page.

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