CVE-2021-29441

CRITICALNVD 8.69.0
EchelonGraph scoreHIGH confidence

“▲” beside the score: it is higher than NVD's CVSS score.

Score elevated to 9.0 because EPSS predicted 83% probability of exploitation within the next 30 days (99th percentile of EPSS-scored CVEs) when EchelonGraph scored this CVE. NVD baseline CVSS 8.6 retained for reference. Confidence: see factors.

Triggered by: EPSS exploit prediction (continuous uplift above 30%)
Sources: EPSS, NVD CVSS v3
Trending — 3 sources updated this weekElevated

Also known asEUVD-2021-0744 (ENISA EUVD) · GHSA-36hp-jr8h-556f (GitHub Security Advisories)Source: ENISA EUVD

9.0EG
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 exploitation likelihood — EPSS 83%
  • Public exploit or proof-of-concept code is available
CISA-KEV: Not listedEPSS PROB: 83%CVSS: 8.6Exploit: Public PoCExposed services: Not assessed

A fix is available — apply it.

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
9.0CRITICALhigh confidence
EG Risk
72
EG Risk 72/100

EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.

How it’s computed (value × EchelonGraph’s weight)
Severity86% × 45%
Impact severity (EG Severity): CVSS 8.6 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation83% × 40%
FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.
Automatability0% × 15%
CISA's BOD 26-04 default: no one has published Automatable for this CVE, and CISA treats it as “no” for a CVE not in KEV.
SSVC (CISA's decision table, applied by EchelonGraph): Track at low, Track* at medium and Attend at high mission impact.
Exploitation public PoC (exploit code on record) · Automatable no (CISA's BOD 26-04 default) · Technical impact total (CISA's BOD 26-04 default). EchelonGraph holds no SSVC assessment of this CVE from CISA: none of these inputs is from 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
83%
EPSS %ILE
99th
KEV
Not listed

What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)

The EG score (9.0): severity, escalated by confirmed exploitation. This CVE's 9.0 is EPSS's lift toward 9.0 from its impact severity (EG Severity, CVSS 8.6 HIGH): a likelihood of exploitation, not impact.

EG Severity
8.6 HIGHCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.NVD CVSS v3 · CVSS v3.0 or v3.1
EG Likelihood
83% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-11-01). FIRST's exploitation probability, not an EchelonGraph model.
Confirmed exploitation
None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
EG Priority
SSVC Track* at medium mission impactTrack at low, Track* at medium and Attend at high mission impact.CISA BOD 26-04: 14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.

SSVC (CISA's decision table, applied by EchelonGraph)Track at low, Track* at medium and Attend at high mission impact.

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

Exploitation public PoC (exploit code on record) · Automatable no (CISA's BOD 26-04 default) · Technical impact total (CISA's BOD 26-04 default). EchelonGraph holds no SSVC assessment of this CVE from CISA: none of these inputs is from 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; Fix on system upgrade if it is not.

The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA's BOD 26-04 default) · Technical impact total (CISA's BOD 26-04 default). Where an input reads “CISA's BOD 26-04 default”, no one has published it for this CVE, and CISA's implementation guidance says: “If “Automatable” and “Technical Impact” information items about a CVE ID are not available and the CVE ID is not in the KEV Catalog, CISA will treat its values as “no” and “total,” respectively, until CISA or a third party provides metadata about the CVE ID. CISA will always provide the Vulnrichment data for a CVE ID listed in the KEV Catalog.” 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

April 27, 2021

Last Modified

November 21, 2024

Advisory Details (3)

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

[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
Web page

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

https://github.com/alibaba/nacos/issues/4701
GitHub advisoryMentions a patch (unverified)

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

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

Patch Availability(1)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
mavencom.alibaba.nacos:nacos-common @ 1.4.1 (fixes < 1.4.1)—ghsa

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Affected Packages

(1 across 1 ecosystem)
Maven(1)
PackageVulnerable rangeFix by version rangeDependents
com.alibaba.nacos:nacos-common0.1.0 ... 1.4.0-BETA (39 versions)
  • every version up to 1.4.1: fixed in 1.4.1
—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 13× in last 7d / 40× 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.

Showing the most recent 91 of 129 refreshes on record for this CVE.

A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. 9 repeat rows among the latest 100 are merged into the row they repeat. The 38 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-11-02 12:21 UTCEG score recompute
  2. 2026-11-02 12:21 UTCGHSA enrichmentGHSA-36hp-jr8h-556f · GitHub severity HIGH
  3. 2026-11-01 16:29 UTCEPSS rescoreEPSS 83% · 99th percentile
  4. 2026-11-01 13:30 UTCGHSA enrichmentGHSA-36hp-jr8h-556f · GitHub severity HIGH
  5. 2026-11-01 08:33 UTCGHSA enrichmentGHSA-36hp-jr8h-556f · GitHub severity HIGH
  6. 2026-11-01 08:33 UTCEG score recompute
  7. 2026-10-31 14:38 UTCEG score recompute
  8. 2026-10-30 16:29 UTCEPSS rescoreEPSS 83% · 99th percentile
  9. 2026-10-29 16:54 UTCEG score recompute
  10. 2026-10-28 18:01 UTCEG score recompute
  11. 2026-10-28 16:28 UTCEPSS rescoreEPSS 83% · 99th percentile
  12. 2026-10-27 19:06 UTCEG score recompute
  13. 2026-10-27 16:28 UTCEPSS rescoreEPSS 83% · 99th percentile
  14. 2026-10-26 20:12 UTCEG score recompute
  15. 2026-10-25 18:30 UTCEG score recompute
  16. 2026-10-25 16:28 UTCEPSS rescoreEPSS 83% · 99th percentile
  17. 2026-10-24 20:30 UTCEG score recompute
  18. 2026-10-24 16:28 UTCEPSS rescoreEPSS 83% · 99th percentile
  19. 2026-10-23 21:38 UTCEG score recompute
  20. 2026-10-22 22:45 UTCEG score recompute
  21. 2026-10-22 16:29 UTCEPSS rescoreEPSS 83% · 99th percentile
  22. 2026-10-21 23:52 UTCEG score recompute
  23. 2026-10-21 16:28 UTCEPSS rescoreEPSS 83% · 99th percentile
  24. 2026-10-21 01:00 UTCEG score recompute
  25. 2026-10-20 02:06 UTCEG score recompute
Show 66 more
  1. 2026-10-19 16:28 UTCEPSS rescoreEPSS 83% · 99th percentile
  2. 2026-10-19 01:18 UTCEG score recompute
  3. 2026-10-18 09:04 UTCEG score recompute
  4. 2026-10-18 02:24 UTCEG score recompute
  5. 2026-10-17 03:31 UTCEG score recompute
  6. 2026-10-16 04:37 UTCEG score recompute
  7. 2026-10-15 16:28 UTCEPSS rescoreEPSS 83% · 99th percentile
  8. 2026-10-15 03:04 UTCEG score recompute
  9. 2026-10-14 16:28 UTCEPSS rescoreEPSS 83% · 99th percentile
  10. 2026-10-13 23:14 UTCEG score recompute
  11. 2026-10-13 16:28 UTCEPSS rescoreEPSS 83% · 99th percentile
  12. 2026-10-12 19:19 UTCEG score recompute
  13. 2026-10-11 23:44 UTCEG score recompute
  14. 2026-10-10 19:56 UTCEPSS rescoreEPSS 83% · 99th percentile
  15. 2026-10-07 23:44 UTCEPSS rescoreEPSS 83% · 99th percentile
  16. 2026-10-03 14:22 UTCEPSS rescoreEPSS 83% · 99th percentile
  17. 2026-10-01 08:40 UTCOSV refresh
  18. 2026-09-30 15:34 UTCEG score recompute
  19. 2026-09-30 15:00 UTCEPSS rescoreEPSS 83% · 99th percentile
  20. 2026-09-24 14:00 UTCEPSS rescoreEPSS 83% · 99th percentile
  21. 2026-09-23 13:44 UTCEPSS rescoreEPSS 88% · 99th percentile
  22. 2026-09-21 20:28 UTCEPSS rescoreEPSS 88% · 99th percentile
  23. 2026-09-18 19:23 UTCEPSS rescoreEPSS 88% · 99th percentile
  24. 2026-09-12 09:10 UTCOSV refresh
  25. 2026-09-06 13:44 UTCEPSS rescoreEPSS 88% · 99th percentile
  26. 2026-09-05 15:25 UTCEPSS rescoreEPSS 88% · 99th percentile
  27. 2026-09-04 13:57 UTCEPSS rescoreEPSS 88% · 99th percentile
  28. 2026-09-01 13:50 UTCEPSS rescoreEPSS 88% · 99th percentile
  29. 2026-08-30 19:14 UTCEPSS rescoreEPSS 88% · 99th percentile
  30. 2026-08-30 01:19 UTCEPSS rescoreEPSS 88% · 99th percentile
  31. 2026-08-28 21:37 UTCEPSS rescoreEPSS 88% · 99th percentile
  32. 2026-08-27 14:22 UTCEPSS rescoreEPSS 88% · 99th percentile
  33. 2026-08-26 14:42 UTCEPSS rescoreEPSS 88% · 99th percentile
  34. 2026-08-24 14:13 UTCEG score recompute▲ 0.10
  35. 2026-08-24 14:12 UTCEPSS rescoreEPSS 88% · 99th percentile
  36. 2026-08-23 00:16 UTCEPSS rescoreEPSS 70% · 99th percentile
  37. 2026-08-21 23:46 UTCEPSS rescoreEPSS 70% · 99th percentile
  38. 2026-08-20 22:52 UTCEPSS rescoreEPSS 70% · 99th percentile
  39. 2026-08-20 04:15 UTCOSV refresh
  40. 2026-08-19 17:01 UTCEPSS rescoreEPSS 70% · 99th percentile
  41. 2026-08-17 13:44 UTCEPSS rescoreEPSS 70% · 99th percentile
  42. 2026-08-16 02:11 UTCEPSS rescoreEPSS 70% · 99th percentile
  43. 2026-08-15 01:27 UTCEPSS rescoreEPSS 70% · 99th percentile
  44. 2026-08-13 21:57 UTCEPSS rescoreEPSS 70% · 99th percentile
  45. 2026-08-12 13:47 UTCEPSS rescoreEPSS 70% · 99th percentile
  46. 2026-08-11 13:38 UTCEPSS rescoreEPSS 70% · 99th percentile
  47. 2026-08-06 13:43 UTCEPSS rescoreEPSS 69% · 99th percentile
  48. 2026-08-05 19:14 UTCEPSS rescoreEPSS 69% · 99th percentile
  49. 2026-08-04 23:11 UTCOSV refresh
  50. 2026-08-01 04:13 UTCEPSS rescoreEPSS 69% · 99th percentile
  51. 2026-07-30 16:25 UTCEPSS rescoreEPSS 69% · 99th percentile
  52. 2026-07-30 01:27 UTCEPSS rescoreEPSS 69% · 99th percentile
  53. 2026-07-28 15:33 UTCEPSS rescoreEPSS 69% · 99th percentile
  54. 2026-07-26 14:52 UTCEPSS rescoreEPSS 69% · 99th percentile
  55. 2026-07-25 14:15 UTCEPSS rescoreEPSS 69% · 99th percentile
  56. 2026-07-24 14:15 UTCEPSS rescoreEPSS 69% · 99th percentile
  57. 2026-07-23 01:59 UTCEG score recompute▲ 0.30
  58. 2026-07-22 22:46 UTCEG score recompute▼ 0.40
  59. 2026-07-22 14:06 UTCEPSS rescoreEPSS 74% · 99th percentile
  60. 2026-07-21 15:22 UTCEPSS rescoreEPSS 74% · 99th percentile
  61. 2026-07-20 17:05 UTCEPSS rescoreEPSS 74% · 99th percentile
  62. 2026-07-19 14:28 UTCEPSS rescoreEPSS 74% · 99th percentile
  63. 2026-07-18 21:29 UTCOSV refresh
  64. 2026-07-15 16:55 UTCEPSS rescoreEPSS 74% · 99th percentile
  65. 2026-07-13 06:10 UTCEPSS rescoreEPSS 74% · 99th percentile
  66. 2026-07-11 08:25 UTCEPSS rescoreEPSS 74% · 99th percentile

Publicly available exploits

(2 references)

Public exploit code is referenced for this CVE (1 GitHub PoC), as is 1 Nuclei detection template. A detection template checks whether a system is affected; it is not necessarily exploit code. Defenders should treat patch urgency accordingly.

  • GitHub PoCbysinks/CVE-2021-29441
    Published Mar 15, 2022
    Open source ↗
  • Nucleihttp/cves/2021/CVE-2021-29441.yaml
    Published May 5, 2021

    Nacos <1.4.1 - Authentication Bypass

    Open source ↗

Frequently asked(5)

What is CVE-2021-29441?
CVE-2021-29441 is a critical-severity vulnerability; its CVE record was 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 the CVE record for CVE-2021-29441 published?
The CVE record for CVE-2021-29441 was published on April 27, 2021. 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 November 21, 2024; the record at its source may have been updated since.
Is CVE-2021-29441 actively exploited?
CVE-2021-29441 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 83% probability of exploitation in the next 30 days (99th percentile of EPSS-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 + FIRST EPSS into a combined EG score of 9.0 (CRITICAL).
How do I remediate CVE-2021-29441?
A fix for CVE-2021-29441 is available: update to the fixed version the vendor names in its advisory.

Dependency Blast Radius

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