CVE-2021-29441

CRITICALNVD 8.69.0▲
EchelonGraph scoreHIGH confidence

Score elevated to 9.0 because EPSS predicts 88% probability of exploitation within the next 30 days (top 0.3% of all CVEs). NVD baseline CVSS 8.6 retained for reference. Confidence: see factors.

Triggered by: EPSS exploit prediction ≥85%
Sources: epss, nvd
Elevated
9.0EG
EchelonGraph verdictPatch this weekExploitation is likely or a public exploit exists.
  • High exploitation likelihood — EPSS 88%
CISA-KEV: Not listedEPSS PROB: 88%CVSS: 8.6Exploit: Elevated riskExposed: 0

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

Nacos is a platform designed for dynamic service discovery and configuration and service management. In Nacos before version 1.4.1, when configured to use authentication (-Dnacos.core.auth.enabled=true) Nacos uses the AuthFilter servlet filter to enforce authentication. This filter has a backdoor that enables Nacos servers to bypass this filter and therefore skip authentication checks. This mechanism relies on the user-agent HTTP header so it can be easily spoofed. This issue may allow any user to carry out any administrative tasks on the Nacos server.

CVSS v3
8.6
EG Score
9.0(high)
EG Risk
80(Track)
EG Risk 80/100SSVC: 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
Severity90% × 45%
Exploitation88% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
88%
EPSS %ILE
100%
KEV
Not listed

Published

April 27, 2021

Last Modified

November 21, 2024

Advisory Details (3)

Auto-updated Sep 1, 2026
Patch available. Sources: github, github_pr.
github_pr

[ISSUE #4701] Fix bypass authentication(identity) problem.

Fix merged in alibaba/nacos PR #4703 on 2021-01-14 — awaiting tagged release

https://github.com/alibaba/nacos/pull/4703
generic

Report a security vulnerability in nacos to bypass authentication(identity) again · Issue #4701 · alibaba/nacos · GitHub

https://github.com/alibaba/nacos/issues/4701
github Patch Available

Authentication Bypass · CVE-2021-29441 · GitHub Advisory Database · GitHub

https://github.com/advisories/GHSA-36hp-jr8h-556f

Affected Packages

(1 across 1 ecosystem)
Maven(1)
PackageVulnerable rangeFixed inDependents
com.alibaba.nacos:nacos-common0.1.0 ... 1.4.0-BETA (39 versions)1.4.1—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 1× in last 7d / 16× 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. 2026-09-18 19:23 UTCEPSS rescore
  2. 2026-09-12 09:10 UTCOSV refresh
  3. 2026-09-06 13:44 UTCEPSS rescore
  4. 2026-09-05 15:25 UTCEPSS rescore
  5. 2026-09-04 13:57 UTCEPSS rescore
  6. 2026-09-01 13:50 UTCEPSS rescore
  7. 2026-08-30 19:14 UTCEPSS rescore
  8. 2026-08-30 01:19 UTCEPSS rescore
  9. 2026-08-28 21:37 UTCEPSS rescore
  10. 2026-08-27 14:22 UTCEPSS rescore
  11. 2026-08-26 14:42 UTCEPSS rescore
  12. 2026-08-24 14:13 UTCEG score recompute▲ 0.10
  13. 2026-08-24 14:12 UTCEPSS rescore
  14. 2026-08-23 00:16 UTCEPSS rescore
  15. 2026-08-21 23:46 UTCEPSS rescore
  16. 2026-08-20 22:52 UTCEPSS rescore
  17. 2026-08-20 04:15 UTCOSV refresh
  18. 2026-08-19 17:01 UTCEPSS rescore
  19. 2026-08-17 13:44 UTCEPSS rescore
  20. 2026-08-16 02:11 UTCEPSS rescore
  21. 2026-08-16 02:11 UTCEPSS rescore
  22. 2026-08-15 01:27 UTCEPSS rescore
  23. 2026-08-13 21:57 UTCEPSS rescore
  24. 2026-08-12 13:47 UTCEPSS rescore
  25. 2026-08-11 13:38 UTCEPSS rescore
Show 65 more
  1. 2026-08-06 13:43 UTCEPSS rescore
  2. 2026-08-05 19:14 UTCEPSS rescore
  3. 2026-08-04 23:11 UTCOSV refresh
  4. 2026-08-01 04:13 UTCEPSS rescore
  5. 2026-07-30 16:25 UTCEPSS rescore
  6. 2026-07-30 16:25 UTCEPSS rescore
  7. 2026-07-30 01:28 UTCEPSS rescore
  8. 2026-07-30 01:27 UTCEPSS rescore
  9. 2026-07-28 15:33 UTCEPSS rescore
  10. 2026-07-26 14:52 UTCEPSS rescore
  11. 2026-07-26 14:52 UTCEPSS rescore
  12. 2026-07-25 14:15 UTCEPSS rescore
  13. 2026-07-24 14:15 UTCEPSS rescore
  14. 2026-07-23 01:59 UTCEG score recompute▲ 0.30
  15. 2026-07-22 22:46 UTCEG score recompute▼ 0.40
  16. 2026-07-22 14:06 UTCEPSS rescore
  17. 2026-07-22 14:06 UTCEPSS rescore
  18. 2026-07-21 15:22 UTCEPSS rescore
  19. 2026-07-21 15:22 UTCEPSS rescore
  20. 2026-07-20 17:05 UTCEPSS rescore
  21. 2026-07-19 14:28 UTCEPSS rescore
  22. 2026-07-18 21:29 UTCOSV refresh
  23. 2026-07-15 16:55 UTCEPSS rescore
  24. 2026-07-15 16:55 UTCEPSS rescore
  25. 2026-07-13 06:10 UTCEPSS rescore
  26. 2026-07-11 08:25 UTCEPSS rescore
  27. 2026-07-11 08:25 UTCEPSS rescore
  28. 2026-07-09 19:07 UTCEPSS rescore
  29. 2026-07-05 02:28 UTCEPSS rescore
  30. 2026-07-04 06:29 UTCEPSS rescore
  31. 2026-07-04 06:29 UTCEPSS rescore
  32. 2026-07-01 15:03 UTCEPSS rescore
  33. 2026-07-01 04:18 UTCOSV refresh
  34. 2026-06-30 23:20 UTCEPSS rescore
  35. 2026-06-30 23:20 UTCEPSS rescore
  36. 2026-06-28 14:05 UTCEPSS rescore
  37. 2026-06-28 04:54 UTCEPSS rescore
  38. 2026-06-28 04:54 UTCEPSS rescore
  39. 2026-06-25 13:48 UTCEPSS rescore
  40. 2026-06-25 13:48 UTCEPSS rescore
  41. 2026-06-24 14:03 UTCEPSS rescore
  42. 2026-06-24 14:03 UTCEPSS rescore
  43. 2026-06-23 21:31 UTCEPSS rescore
  44. 2026-06-23 21:31 UTCEPSS rescore
  45. 2026-06-21 14:55 UTCEPSS rescore
  46. 2026-06-21 14:54 UTCEPSS rescore
  47. 2026-06-21 01:58 UTCEPSS rescore
  48. 2026-06-21 01:58 UTCEPSS rescore
  49. 2026-06-18 17:51 UTCEPSS rescore
  50. 2026-06-18 17:51 UTCEPSS rescore
  51. 2026-06-16 17:51 UTCEPSS rescore
  52. 2026-06-15 17:46 UTCEPSS rescore
  53. 2026-06-13 07:13 UTCOSV refresh
  54. 2026-06-12 23:10 UTCEPSS rescore
  55. 2026-06-11 13:58 UTCEPSS rescore
  56. 2026-06-05 06:09 UTCEPSS rescore
  57. 2026-06-05 06:09 UTCEPSS rescore
  58. 2026-06-01 13:50 UTCEPSS rescore
  59. 2026-06-01 13:50 UTCEPSS rescore
  60. 2026-05-29 13:42 UTCEPSS rescore
  61. 2026-05-27 13:39 UTCEPSS rescore
  62. 2026-05-27 13:39 UTCEPSS rescore
  63. 2026-05-26 17:23 UTCEG score recompute
  64. 2026-05-26 07:17 UTCEPSS rescore
  65. 2026-05-26 07:17 UTCEPSS rescore

Publicly available exploits

(2 references)

Working exploit code is in the public domain (1 GitHub PoC). Defenders should treat patch urgency accordingly — public PoCs typically lead to mass-exploitation within 24-72 hours.

  • GitHub PoCbysinks/CVE-2021-29441
    First seen Mar 15, 2022
    Open source ↗
  • Nucleihttp/cves/2021/CVE-2021-29441.yaml
    First seen Jan 1, 2021

    Nacos <1.4.1 - Authentication Bypass

    Open source ↗

Frequently asked(5)

What is CVE-2021-29441?
CVE-2021-29441 is a critical vulnerability published on April 27, 2021. Nacos is a platform designed for dynamic service discovery and configuration and service management. In Nacos before version 1.4.1, when configured to use authentication (-Dnacos.core.auth.enabled=true) Nacos uses the AuthFilter servlet filter to enforce authentication. This filter has a backdoor…
When was CVE-2021-29441 disclosed?
CVE-2021-29441 was first published in the National Vulnerability Database on April 27, 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-2021-29441 actively exploited?
CVE-2021-29441 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 88% probability of exploitation in the next 30 days, which ranks it in the top 0.2% of all scored CVEs.
What is the CVSS score of CVE-2021-29441?
CVE-2021-29441 has a CVSS v3 base score of 8.6 (NVD). EchelonGraph synthesises NVD + CISA KEV + FIRST EPSS + GHSA into a combined EG score of 9.0.
How do I remediate CVE-2021-29441?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-29441, 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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