---
title: "CVE-2021-29441: Authentication bypass | CubePath"
description: "Nacos is a platform designed for dynamic service discovery and configuration and service management. In Nacos before version 1.4.1, when configured…"
language: en
source: https://cubepath.com/security/cve/CVE-2021-29441
---

# CVE-2021-29441: Authentication bypass | CubePath

## Description

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.

Official description from the CVE record, published by GitHub\_M. Copyright © 1999-2026 The MITRE Corporation. See [/security/cve/legal](https://cubepath.com/security/cve/legal) for the CVE license. [View the record on cve.org](https://www.cve.org/CVERecord?id=CVE-2021-29441)

## Key data

### CVSS 3.1 High 8.6

Score published by GitHub\_M in the CVE record.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N

| Metric                 | Value   | What it means                                                                       |
| ---------------------- | ------- | ----------------------------------------------------------------------------------- |
| Attack vector          | Network | The vulnerable component can be reached over a network, possibly from the Internet. |
| Attack complexity      | Low     | No special conditions are needed. The attack can be repeated at will.               |
| Privileges required    | None    | No account or privileges are needed.                                                |
| User interaction       | None    | No action from any user is needed.                                                  |
| Scope                  | Changed | The impact can reach other components beyond the vulnerable one.                    |
| Confidentiality impact | High    | Serious or total effect on the secrecy of data.                                     |
| Integrity impact       | None    | No effect on the trustworthiness of data.                                           |
| Availability impact    | None    | No effect on availability.                                                          |

CVSS is owned and managed by FIRST.Org, Inc. (FIRST) and is used by permission. Each CVSS score on this site is shown together with its vector string, as published in the CVE record by the source named next to it. Learn more at [first.org/cvss](https://www.first.org/cvss/) .

### EPSS

Exploit Prediction Scoring System by FIRST: an estimate of the probability that exploitation activity will be observed in the next 30 days.

Score

0.83236 (83.2% probability)

Percentile

99.7%

Scores of

Nov 10, 2026

Model

v2026.06.15

### Weakness (CWE)

CWE catalog version 5.0.

CWE names: Copyright © 2006-2026, The MITRE Corporation. See [/security/cve/legal](https://cubepath.com/security/cve/legal) for the CWE license.

- [CWE-290](https://cwe.mitre.org/data/definitions/290.html) Authentication Bypass by Spoofing

## Affected products

Products listed in the CVE record, as the CNA published them.

- alibaba nacos

  - affected: < 1.4.1

## References

Links listed in the CVE record. They lead to other sites, which CubePath does not control.

- [github.com/alibaba/nacos/issues/4701](https://github.com/alibaba/nacos/issues/4701)
- [github.com/advisories/GHSA-36hp-jr8h-556f](https://github.com/advisories/GHSA-36hp-jr8h-556f)
- [github.com/alibaba/nacos/pull/4703](https://github.com/alibaba/nacos/pull/4703)

## Timeline

1. ID reserved Mar 30, 2021
2. Record published Apr 27, 2021
3. Record last updated Aug 3, 2024

## Look up another CVE

## About CubePath

CubePath is a cloud provider with data centers in Europe and the United States. It offers VPS, bare metal servers and DDoS protection.

[Cloud VPS](https://cubepath.com/vps) [DDoS protection](https://cubepath.com/ddos-protection)

Data from the CVE Program (MITRE), CISA KEV and FIRST EPSS. CVSS is owned by FIRST and used by permission. Not affiliated with or endorsed by MITRE, CISA or FIRST. Data as of Nov 10, 2026, 20:03 UTC. [Sources and licenses](https://cubepath.com/security/cve/legal)