CVE-2021-23406

HIGHNVD 8.18.1—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 8.1 under NVD CVSS v3. EPSS exploit probability: 2.9% (86th percentile of EPSS-scored CVEs). 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, nvd
8.1EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 2.9%CVSS: 8.1Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

This affects the package pac-resolver before 5.0.0. This can occur when used with untrusted input, due to unsafe PAC file handling. NOTE: The fix for this vulnerability is applied in the node-degenerator library, a dependency written by the same maintainer.

CVSS v3
8.1
EG Score
8.1HIGHmedium confidence
EG Risk
42
EG Risk 42/100CISA SSVC

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
Severity81% × 45%
Exploitation3% × 40%
Automatability30% × 15%
CISA SSVC: Track at low or medium mission impact; Track or Attend at high (mission-essential systems).
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
2.9%
EPSS %ILE
86th
KEV
Not listed

CISA SSVCTrack at low or medium mission impact; Track or 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 (no KEV listing, exploit record or EPSS ≥ 50%) · Automatable unknown (not published for this CVE) · Technical impact partial (CVSS below 9.0). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table

Published

August 24, 2021

Last Modified

November 21, 2024

Advisory Details (5)

Auto-updated Sep 11, 2026
⚠️ Active exploitation confirmed. Patch available. Sources: github_commit, github_release.
generic🔴 Active Exploitation

Remote Code Execution (RCE) in pac-resolver | CVE-2021-23406 | Snyk

https://snyk.io/vuln/SNYK-JS-PACRESOLVER-1564857
generic🔴 Active Exploitation

Remote Code Execution (RCE) in org.webjars.npm:pac-resolver | CVE-2021-23406 | Snyk

https://snyk.io/vuln/SNYK-JAVA-ORGWEBJARSNPM-1568506
github_release Patch Available

Release 5.0.0 (TooTallNate/node-pac-resolver)

Patch available: TooTallNate/node-pac-resolver 5.0.0

https://github.com/TooTallNate/node-pac-resolver/releases/tag/5.0.0
github_commit Patch Available

commit ccc344535413 (TooTallNate/node-degenerator)

Patch available: TooTallNate/node-degenerator 3.0.1 (contains commit ccc344535413)

https://github.com/TooTallNate/node-degenerator/commit/ccc3445354135398b6eb1a04c7d27c13b833f2d5
github_commit Patch Available

commit 9d25bb67d957 (TooTallNate/node-degenerator)

Patch available: TooTallNate/node-degenerator 3.0.1 (contains commit 9d25bb67d957)

https://github.com/TooTallNate/node-degenerator/commit/9d25bb67d957bc2e5425fea7bf7a58b3fc64ff9e

Affected Packages

(2 across 1 ecosystem)
npm(2)
PackageVulnerable rangeFix by version rangeDependents
degenerator—
  • every version up to 3.0.1: fixed in 3.0.1
—
pac-resolver—
  • every version up to 5.0.0: fixed in 5.0.0
—

Data Freshness Timeline

(refreshed 8× in last 7d / 34× 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.

Showing the most recent 100 of 179 total refreshes for this CVE.

  1. 2026-10-05 17:40 UTCEPSS rescore
  2. 2026-10-04 23:18 UTCEPSS rescore
  3. 2026-10-03 14:22 UTCEPSS rescore
  4. 2026-10-03 14:22 UTCEPSS rescore
  5. 2026-10-02 16:22 UTCEPSS rescore
  6. 2026-10-01 19:46 UTCEPSS rescore
  7. 2026-09-30 15:31 UTCEG score recompute
  8. 2026-09-30 15:00 UTCEPSS rescore
  9. 2026-09-28 13:47 UTCEPSS rescore
  10. 2026-09-27 13:41 UTCEPSS rescore
  11. 2026-09-26 15:54 UTCEPSS rescore
  12. 2026-09-26 15:54 UTCEPSS rescore
  13. 2026-09-26 00:21 UTCEPSS rescore
  14. 2026-09-25 18:45 UTCOSV refresh
  15. 2026-09-24 14:00 UTCEPSS rescore
  16. 2026-09-24 14:00 UTCEPSS rescore
  17. 2026-09-23 13:44 UTCEPSS rescore
  18. 2026-09-22 14:44 UTCEPSS rescore
  19. 2026-09-21 20:28 UTCEPSS rescore
  20. 2026-09-19 15:37 UTCEPSS rescore
  21. 2026-09-18 19:23 UTCEPSS rescore
  22. 2026-09-17 19:23 UTCEPSS rescore
  23. 2026-09-16 14:05 UTCEPSS rescore
  24. 2026-09-16 14:04 UTCEPSS rescore
  25. 2026-09-15 03:06 UTCEPSS rescore
Show 75 more
  1. 2026-09-13 16:43 UTCEPSS rescore
  2. 2026-09-12 14:57 UTCEPSS rescore
  3. 2026-09-11 09:33 UTCEPSS rescore
  4. 2026-09-10 09:29 UTCEPSS rescore
  5. 2026-09-08 21:56 UTCEPSS rescore
  6. 2026-09-07 15:58 UTCEPSS rescore
  7. 2026-09-06 13:44 UTCEPSS rescore
  8. 2026-09-06 13:44 UTCEPSS rescore
  9. 2026-09-06 09:30 UTCOSV refresh
  10. 2026-09-05 15:25 UTCEPSS rescore
  11. 2026-09-04 13:57 UTCEPSS rescore
  12. 2026-09-04 05:03 UTCEPSS rescore
  13. 2026-09-02 14:08 UTCEPSS rescore
  14. 2026-09-01 13:50 UTCEPSS rescore
  15. 2026-09-01 03:32 UTCEPSS rescore
  16. 2026-08-30 19:14 UTCEPSS rescore
  17. 2026-08-30 01:19 UTCEPSS rescore
  18. 2026-08-28 21:37 UTCEPSS rescore
  19. 2026-08-27 14:22 UTCEPSS rescore
  20. 2026-08-26 14:42 UTCEPSS rescore
  21. 2026-08-25 13:45 UTCEPSS rescore
  22. 2026-08-23 00:16 UTCEPSS rescore
  23. 2026-08-21 23:46 UTCEPSS rescore
  24. 2026-08-20 22:52 UTCEPSS rescore
  25. 2026-08-19 20:04 UTCOSV refresh
  26. 2026-08-19 17:01 UTCEPSS rescore
  27. 2026-08-18 13:45 UTCEPSS rescore
  28. 2026-08-17 13:43 UTCEPSS rescore
  29. 2026-08-16 14:52 UTCEPSS rescore
  30. 2026-08-16 02:11 UTCEPSS rescore
  31. 2026-08-15 01:27 UTCEPSS rescore
  32. 2026-08-13 21:57 UTCEPSS rescore
  33. 2026-08-12 13:47 UTCEPSS rescore
  34. 2026-08-11 13:38 UTCEPSS rescore
  35. 2026-08-08 16:33 UTCEPSS rescore
  36. 2026-08-07 16:23 UTCEPSS rescore
  37. 2026-08-06 13:43 UTCEPSS rescore
  38. 2026-08-05 19:14 UTCEPSS rescore
  39. 2026-08-04 15:32 UTCOSV refresh
  40. 2026-08-04 15:06 UTCEPSS rescore
  41. 2026-08-04 10:34 UTCEPSS rescore
  42. 2026-08-03 10:32 UTCEPSS rescore
  43. 2026-08-02 02:24 UTCEPSS rescore
  44. 2026-08-01 04:12 UTCEPSS rescore
  45. 2026-07-30 16:25 UTCEPSS rescore
  46. 2026-07-30 01:27 UTCEPSS rescore
  47. 2026-07-30 01:27 UTCEPSS rescore
  48. 2026-07-26 14:52 UTCEPSS rescore
  49. 2026-07-25 14:15 UTCEPSS rescore
  50. 2026-07-24 14:15 UTCEPSS rescore
  51. 2026-07-23 14:15 UTCEPSS rescore
  52. 2026-07-23 01:57 UTCEG score recompute
  53. 2026-07-22 22:44 UTCEG score recompute
  54. 2026-07-22 14:05 UTCEPSS rescore
  55. 2026-07-21 15:22 UTCEPSS rescore
  56. 2026-07-21 15:22 UTCEPSS rescore
  57. 2026-07-20 17:04 UTCEPSS rescore
  58. 2026-07-19 14:28 UTCEPSS rescore
  59. 2026-07-19 02:26 UTCEPSS rescore
  60. 2026-07-18 13:29 UTCOSV refresh
  61. 2026-07-18 10:02 UTCEPSS rescore
  62. 2026-07-16 17:00 UTCEPSS rescore
  63. 2026-07-15 16:55 UTCEPSS rescore
  64. 2026-07-15 16:55 UTCEPSS rescore
  65. 2026-07-15 01:57 UTCEPSS rescore
  66. 2026-07-13 22:27 UTCEPSS rescore
  67. 2026-07-13 22:27 UTCEPSS rescore
  68. 2026-07-13 06:10 UTCEPSS rescore
  69. 2026-07-13 06:10 UTCEPSS rescore
  70. 2026-07-12 05:44 UTCEPSS rescore
  71. 2026-07-12 05:44 UTCEPSS rescore
  72. 2026-07-11 08:25 UTCEPSS rescore
  73. 2026-07-09 19:07 UTCEPSS rescore
  74. 2026-07-08 15:12 UTCEPSS rescore
  75. 2026-07-07 13:43 UTCEPSS rescore

Frequently asked(5)

What is CVE-2021-23406?
CVE-2021-23406 is a high vulnerability published on August 24, 2021. This affects the package pac-resolver before 5.0.0. This can occur when used with untrusted input, due to unsafe PAC file handling. NOTE: The fix for this vulnerability is applied in the node-degenerator library, a dependency written by the same maintainer.
When was CVE-2021-23406 disclosed?
CVE-2021-23406 was first published on August 24, 2021, with the most recent update on November 21, 2024. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2021-23406 actively exploited?
CVE-2021-23406 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 2.9% probability of exploitation in the next 30 days (86th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2021-23406?
CVE-2021-23406 has a CVSS v3 base score of 8.1 (NVD).
How do I remediate CVE-2021-23406?
A fix for CVE-2021-23406 is available: update to the fixed version the vendor names in its advisory.

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