CVE-2021-29441

Authentication bypass

CRITICAL
9.8
CVSS Score
Published: April 27, 2021 at 08:20 PM UTC
Updated: June 17, 2026 at 03:47 AM UTC
1 product affected across 1 vendorNacos

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Severity
CRITICAL9.8
Exploit prediction
EPSS 83%

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 1.4.1
Affected range stops below 1.4.1, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

References (3)

x_refsource_CONFIRMExploitThird Party Advisory
https://github.com/advisories/GHSA-36hp-jr8h-556f
x_refsource_MISCExploitThird Party Advisory
https://github.com/alibaba/nacos/issues/4701
x_refsource_MISCPatchThird Party Advisory
https://github.com/alibaba/nacos/pull/4703

CVSS

Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
HIGH
Availability
HIGH
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-290

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