CVE-2021-21322

CRITICALNVD 10.010.0—
EchelonGraph scoreMEDIUM confidence

This critical-severity CVE scores 10.0 under NVD CVSS v3. EPSS exploit probability: 0.2%, top 60% 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, nvd
10.0
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 2%CVSS: 10.0Exploit: NoneExposed: 0

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

fastify-http-proxy is an npm package which is a fastify plugin for proxying your http requests to another server, with hooks. By crafting a specific URL, it is possible to escape the prefix of the proxied backend service. If the base url of the proxied server is /pub/, a user expect that accessing /priv on the target service would not be possible. In affected versions, it is possible. This is fixed in version 4.3.1.

CVSS v3
10.0
EG Score
10.0(medium)
EPSS
77.5%
KEV
Not listed

Published

March 2, 2021

Last Modified

November 21, 2024

Advisory Details (2)

Auto-updated Jul 11, 2026
Patch available. Sources: github_commit, github.
github Patch Available

Prefix escape · Advisory · fastify/fastify-http-proxy · GitHub

https://github.com/fastify/fastify-http-proxy/security/advisories/GHSA-c4qr-gmr9-v23w
github_commit Patch Available

commit 02d9b43c770a (fastify/fastify-http-proxy)

Patch available: fastify/fastify-http-proxy v8.1.0 (contains commit 02d9b43c770a)

https://github.com/fastify/fastify-http-proxy/commit/02d9b43c770aa16bc44470edecfaeb7c17985016

Vendor Advisories for CVE-2021-21322(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)
npm(1)
PackageVulnerable rangeFixed inDependents
fastify-http-proxy—4.3.1—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 9× in last 7d / 47× 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. 2026-07-11 08:25 UTCEPSS rescore
  2. 2026-07-09 19:07 UTCEPSS rescore
  3. 2026-07-08 15:12 UTCEPSS rescore
  4. 2026-07-07 13:43 UTCEPSS rescore
  5. 2026-07-06 16:25 UTCEPSS rescore
  6. 2026-07-06 02:21 UTCEPSS rescore
  7. 2026-07-06 02:21 UTCEPSS rescore
  8. 2026-07-05 02:28 UTCEPSS rescore
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  10. 2026-07-04 06:29 UTCEPSS rescore
  11. 2026-07-04 06:29 UTCEPSS rescore
  12. 2026-07-02 16:57 UTCEPSS rescore
  13. 2026-07-01 15:03 UTCEPSS rescore
  14. 2026-07-01 07:48 UTCOSV refresh
  15. 2026-06-30 23:20 UTCEPSS rescore
  16. 2026-06-30 23:20 UTCEPSS rescore
  17. 2026-06-29 14:04 UTCEPSS rescore
  18. 2026-06-29 14:04 UTCEPSS rescore
  19. 2026-06-28 14:05 UTCEPSS rescore
  20. 2026-06-28 04:54 UTCEPSS rescore
  21. 2026-06-28 04:54 UTCEPSS rescore
  22. 2026-06-27 03:06 UTCEPSS rescore
  23. 2026-06-27 03:06 UTCEPSS rescore
  24. 2026-06-25 13:48 UTCEPSS rescore
  25. 2026-06-25 13:48 UTCEPSS rescore
Show 57 more
  1. 2026-06-24 14:03 UTCEPSS rescore
  2. 2026-06-24 14:03 UTCEPSS rescore
  3. 2026-06-23 21:31 UTCEPSS rescore
  4. 2026-06-23 21:31 UTCEPSS rescore
  5. 2026-06-22 14:24 UTCEPSS rescore
  6. 2026-06-22 14:23 UTCEPSS rescore
  7. 2026-06-21 14:54 UTCEPSS rescore
  8. 2026-06-21 14:54 UTCEPSS rescore
  9. 2026-06-21 01:58 UTCEPSS rescore
  10. 2026-06-21 01:57 UTCEPSS rescore
  11. 2026-06-19 19:24 UTCEPSS rescore
  12. 2026-06-19 19:24 UTCEPSS rescore
  13. 2026-06-18 17:51 UTCEPSS rescore
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  15. 2026-06-17 17:51 UTCEPSS rescore
  16. 2026-06-16 17:50 UTCEPSS rescore
  17. 2026-06-15 17:46 UTCEPSS rescore
  18. 2026-06-14 23:15 UTCEPSS rescore
  19. 2026-06-13 22:58 UTCEPSS rescore
  20. 2026-06-13 12:43 UTCOSV refresh
  21. 2026-06-12 23:10 UTCEPSS rescore
  22. 2026-06-12 23:10 UTCEPSS rescore
  23. 2026-06-11 13:58 UTCEPSS rescore
  24. 2026-06-10 22:16 UTCEPSS rescore
  25. 2026-06-10 22:16 UTCEPSS rescore
  26. 2026-06-10 13:20 UTCEPSS rescore
  27. 2026-06-08 14:15 UTCEPSS rescore
  28. 2026-06-08 14:15 UTCEPSS rescore
  29. 2026-06-07 15:23 UTCEPSS rescore
  30. 2026-06-07 15:23 UTCEPSS rescore
  31. 2026-06-06 13:46 UTCEPSS rescore
  32. 2026-06-06 13:46 UTCEPSS rescore
  33. 2026-06-06 13:46 UTCEPSS rescore
  34. 2026-06-05 22:45 UTCEPSS rescore
  35. 2026-06-05 22:45 UTCEPSS rescore
  36. 2026-06-05 06:09 UTCEPSS rescore
  37. 2026-06-05 06:09 UTCEPSS rescore
  38. 2026-06-05 06:08 UTCEPSS rescore
  39. 2026-06-04 13:10 UTCEPSS rescore
  40. 2026-06-02 20:11 UTCEPSS rescore
  41. 2026-06-02 20:11 UTCEPSS rescore
  42. 2026-06-01 13:50 UTCEPSS rescore
  43. 2026-06-01 13:50 UTCEPSS rescore
  44. 2026-05-31 22:29 UTCEPSS rescore
  45. 2026-05-31 22:29 UTCEPSS rescore
  46. 2026-05-31 00:15 UTCEPSS rescore
  47. 2026-05-31 00:15 UTCEPSS rescore
  48. 2026-05-29 13:42 UTCEPSS rescore
  49. 2026-05-28 13:43 UTCEPSS rescore
  50. 2026-05-28 13:43 UTCEPSS rescore
  51. 2026-05-27 13:39 UTCEPSS rescore
  52. 2026-05-26 20:16 UTCEG score recompute
  53. 2026-05-26 13:42 UTCEPSS rescore
  54. 2026-05-26 13:42 UTCEPSS rescore
  55. 2026-05-26 07:17 UTCEPSS rescore
  56. 2026-05-26 07:17 UTCEPSS rescore
  57. 2026-05-24 16:49 UTCEPSS rescore

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2021-21322?
CVE-2021-21322 is a critical vulnerability published on March 2, 2021. fastify-http-proxy is an npm package which is a fastify plugin for proxying your http requests to another server, with hooks. By crafting a specific URL, it is possible to escape the prefix of the proxied backend service. If the base url of the proxied server is /pub/, a user expect that accessing…
When was CVE-2021-21322 disclosed?
CVE-2021-21322 was first published in the National Vulnerability Database on March 2, 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-2021-21322 actively exploited?
CVE-2021-21322 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 77.5% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2021-21322?
CVE-2021-21322 has a CVSS v3 base score of 10.0 (NVD).
How do I remediate CVE-2021-21322?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-21322, 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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