CVE-2021-29441

Name: CVE-2021-29441
Creator: NVD / NIST
Published: 2021-04-27T21:15:07.993+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

CRITICALCVSS 9.8/10EPSS 74.82%

Last modified Jun 17, 2026

CVE-2021-29441 is a critical-severity vulnerability rated 9.8/10 on the CVSS scale. 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. EPSS estimates a 74.82% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1

9.8/10

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

EPSS Probability

74.82%

99.4th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Alibaba	Nacos	< 1.4.1

References

https://github.com/advisories/GHSA-36hp-jr8h-556fExploit, Third Party Advisory
https://github.com/alibaba/nacos/issues/4701Exploit, Third Party Advisory
https://github.com/alibaba/nacos/pull/4703Patch, Third Party Advisory
https://github.com/advisories/GHSA-36hp-jr8h-556fExploit, Third Party Advisory
https://github.com/alibaba/nacos/issues/4701Exploit, Third Party Advisory
https://github.com/alibaba/nacos/pull/4703Patch, Third Party Advisory

Timeline

Published: Apr 27, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-29441?

How severe is CVE-2021-29441?

CVE-2021-29441 has a CVSS score of 9.8/10 (CRITICAL severity). The EPSS model estimates a 74.82% probability of exploitation in the next 30 days.

How do I fix CVE-2021-29441?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-29441?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST