CVE-2021-29441
CVSS v3
9.8
CRITICAL
EPSS Score
83.5 %
exploit probability, as of 2026-10-05
CISA KEV
No
known exploited
Exploitation
—
SSVC status
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.
Technical details
- Published
- 2021-04-27
Frequently asked questions
What is CVE-2021-29441?
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.
Is CVE-2021-29441 actively exploited?
Active exploitation of CVE-2021-29441 has not been confirmed. Its EPSS score was 83.5% on 2026-10-05, the estimated probability of exploitation in the next 30 days.
What is the CVSS score for CVE-2021-29441?
CVE-2021-29441 has a CVSS v3 base score of 9.8 (CRITICAL severity).
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