CVE-2026-66754

MEDIUMPre-NVD 5.95.9—
EchelonGraph scoreHIGH confidence

Score 5.9 from GitHub Security Advisory (severity: HIGH) published 2026-07-28. a secondary CVSS source baseline 5.9; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 3 sources updated this weekElevated
5.9EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 5.9Exploit: Elevated riskExposed: 0

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

Rouille 0.1.6 through 3.6.2 contains a reachable assertion vulnerability in the Request::remove_prefix function that allows remote unauthenticated attackers to crash the server by sending a crafted percent-encoded URL. Attackers can send a request whose decoded path matches a configured prefix while the raw percent-encoded path does not, causing the assert! to fail and triggering either a 500 error or full process termination depending on the panic configuration.

CVSS v3
5.9
EG Score
5.9(high)
EG Risk
43(Track)
EG Risk 43/100SSVC: 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
Severity59% × 45%
Exploitation40% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
33%
KEV
Not listed

Published

July 28, 2026

Last Modified

July 30, 2026

Advisory Details (2)

Auto-updated Jul 28, 2026
🔬 Proof of concept available. No patch confirmed yet.
generic

Rouille 0.1.6 - 3.6.2 Reachable Assertion DoS via remove_prefix percent-encoding | Advisories | VulnCheck

https://www.vulncheck.com/advisories/rouille-reachable-assertion-dos-via-remove-prefix-percent-encoding
generic🟡 PoC Available

GitHub - theopaid/Remote-Denial-of-Service-via-Reachable-Assertion-in-URL-Prefix-Handling-rouille-: Security Advisory: Remote Denial of Service via Reachable Assertion in URL Prefix Handling (rouille) · GitHub

https://github.com/theopaid/Remote-Denial-of-Service-via-Reachable-Assertion-in-URL-Prefix-Handling-rouille-

Vendor Advisories for CVE-2026-66754(1)

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

Affected Packages

(1 across 1 ecosystem)
Debian:14(1)
PackageVulnerable rangeFixed inDependents
rust-rouille3.6.2+20250617+ds-1, 3.6.2+20250617+ds-2, 3.6.2+20250617+ds-3——

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 17× in last 7d / 82× 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. 2026-08-26 14:47 UTCEPSS rescore
  2. 2026-08-26 02:23 UTCEG score recompute
  3. 2026-08-26 02:23 UTCGHSA enrichment
  4. 2026-08-25 13:49 UTCEPSS rescore
  5. 2026-08-25 00:01 UTCEG score recompute
  6. 2026-08-25 00:01 UTCGHSA enrichment
  7. 2026-08-23 21:38 UTCEG score recompute
  8. 2026-08-23 21:38 UTCGHSA enrichment
  9. 2026-08-23 00:19 UTCEPSS rescore
  10. 2026-08-22 19:16 UTCEG score recompute
  11. 2026-08-22 19:16 UTCGHSA enrichment
  12. 2026-08-21 23:49 UTCEPSS rescore
  13. 2026-08-21 16:53 UTCEG score recompute
  14. 2026-08-21 16:53 UTCGHSA enrichment
  15. 2026-08-20 22:56 UTCEPSS rescore
  16. 2026-08-20 14:26 UTCEG score recompute
  17. 2026-08-20 14:26 UTCGHSA enrichment
  18. 2026-08-19 17:04 UTCEPSS rescore
  19. 2026-08-19 11:45 UTCEG score recompute
  20. 2026-08-19 11:45 UTCGHSA enrichment
  21. 2026-08-18 13:48 UTCEPSS rescore
  22. 2026-08-18 09:22 UTCEG score recompute
  23. 2026-08-18 09:22 UTCGHSA enrichment
  24. 2026-08-17 13:47 UTCEPSS rescore
  25. 2026-08-17 06:59 UTCEG score recompute
Show 57 more
  1. 2026-08-17 06:59 UTCGHSA enrichment
  2. 2026-08-16 14:56 UTCEPSS rescore
  3. 2026-08-16 04:37 UTCEG score recompute
  4. 2026-08-16 04:37 UTCGHSA enrichment
  5. 2026-08-15 02:14 UTCEG score recompute
  6. 2026-08-15 02:14 UTCGHSA enrichment
  7. 2026-08-15 01:30 UTCEPSS rescore
  8. 2026-08-13 23:52 UTCEG score recompute
  9. 2026-08-13 23:52 UTCGHSA enrichment
  10. 2026-08-13 22:00 UTCEPSS rescore
  11. 2026-08-12 21:29 UTCEG score recompute
  12. 2026-08-12 21:29 UTCGHSA enrichment
  13. 2026-08-12 13:51 UTCEPSS rescore
  14. 2026-08-11 19:06 UTCEG score recompute
  15. 2026-08-11 19:06 UTCGHSA enrichment
  16. 2026-08-11 00:00 UTCEPSS rescore
  17. 2026-08-10 16:41 UTCGHSA enrichment
  18. 2026-08-09 14:18 UTCEG score recompute
  19. 2026-08-09 14:18 UTCGHSA enrichment
  20. 2026-08-09 13:47 UTCEPSS rescore
  21. 2026-08-08 16:37 UTCEPSS rescore
  22. 2026-08-08 11:56 UTCEG score recompute
  23. 2026-08-08 11:56 UTCGHSA enrichment
  24. 2026-08-07 09:33 UTCEG score recompute
  25. 2026-08-07 09:33 UTCGHSA enrichment
  26. 2026-08-06 13:47 UTCEPSS rescore
  27. 2026-08-06 07:11 UTCEG score recompute
  28. 2026-08-06 07:11 UTCGHSA enrichment
  29. 2026-08-05 19:17 UTCEPSS rescore
  30. 2026-08-05 19:17 UTCEPSS rescore
  31. 2026-08-05 04:49 UTCEG score recompute
  32. 2026-08-05 04:49 UTCGHSA enrichment
  33. 2026-08-04 15:10 UTCEPSS rescore
  34. 2026-08-04 10:39 UTCEPSS rescore
  35. 2026-08-04 02:17 UTCEG score recompute
  36. 2026-08-04 02:17 UTCGHSA enrichment
  37. 2026-08-03 10:36 UTCEPSS rescore
  38. 2026-08-02 23:55 UTCEG score recompute
  39. 2026-08-02 23:55 UTCGHSA enrichment
  40. 2026-08-02 02:27 UTCEPSS rescore
  41. 2026-08-01 21:32 UTCEG score recompute
  42. 2026-08-01 21:32 UTCGHSA enrichment
  43. 2026-08-01 04:16 UTCEPSS rescore
  44. 2026-07-31 19:09 UTCGHSA enrichment
  45. 2026-07-30 16:45 UTCEG score recompute
  46. 2026-07-30 16:45 UTCGHSA enrichment
  47. 2026-07-30 16:28 UTCEPSS rescore
  48. 2026-07-30 01:30 UTCEPSS rescore
  49. 2026-07-29 14:20 UTCEG score recompute
  50. 2026-07-29 14:20 UTCGHSA enrichment
  51. 2026-07-29 13:59 UTCEG score recompute
  52. 2026-07-29 13:59 UTCGHSA enrichment
  53. 2026-07-28 17:23 UTCEG score recompute▼ 1.60
  54. 2026-07-28 17:21 UTCNVD updateCVSS v3 → 5.9 · severity → MEDIUM
  55. 2026-07-28 16:40 UTCEG score recompute
  56. 2026-07-28 16:14 UTCEG score recompute
  57. 2026-07-28 16:13 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-66754?
CVE-2026-66754 is a medium vulnerability published on July 28, 2026. Rouille 0.1.6 through 3.6.2 contains a reachable assertion vulnerability in the Request::remove_prefix function that allows remote unauthenticated attackers to crash the server by sending a crafted percent-encoded URL. Attackers can send a request whose decoded path matches a configured prefix…
When was CVE-2026-66754 disclosed?
CVE-2026-66754 was first published in the National Vulnerability Database on July 28, 2026, with the most recent update on July 30, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-66754 actively exploited?
CVE-2026-66754 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 66.9% of all scored CVEs.
What is the CVSS score of CVE-2026-66754?
CVE-2026-66754 has a CVSS v3 base score of 5.9 (NVD).
How do I remediate CVE-2026-66754?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-66754, 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

See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-66754

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