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Security Advisories: MDE2OlNlY3VyaXR5QWR2aXNvcnlHSFNBLTM2aHAtanI4aC01NTZm

Authentication Bypass

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.

The following request to the configuration endpoint gets rejected as we are not providing any credentials:

❯ curl -X POST ""
{"timestamp":"2020-12-02T14:33:57.154+0000","status":403,"error":"Forbidden","message":"unknown user!","path":"/nacos/v1/cs/configs"}                                                                                                       

However the following one gets accepted by using the Nacos-Server user-agent header:

❯ curl -X POST -A Nacos-Server ""


This issue may allow any user to carry out any administrative tasks on the Nacos server.

Source: GitHub Advisory Database
Origin: Unspecified
Severity: High
Classification: General
Published: over 2 years ago
Updated: 10 months ago

Identifiers: GHSA-36hp-jr8h-556f, CVE-2021-29441

Affected Packages
Versions: < 1.4.1
Fixed in: 1.4.1