CVE-2019-20933: 
InfluxDB vulnerability analysis and mitigation

InfluxDB before version 1.7.6 contained an authentication bypass vulnerability (CVE-2019-20933) in the authenticate function within services/httpd/handler.go. The vulnerability stems from the ability to use a JWT token with an empty SharedSecret (shared secret) parameter (NVD, CVE).

The vulnerability exists in the authentication mechanism where the system fails to properly validate JWT tokens. Specifically, the code in the authenticate function does not check whether the SharedSecret is empty before processing bearer authentication. This oversight allows attackers to generate their own JWT tokens and successfully authenticate to the InfluxDB instance (GitHub Commit, GitHub Issue).

If InfluxDB is left in its default state, this vulnerability allows attackers to bypass authentication by generating their own JWT tokens and gain unauthorized access to the InfluxDB instance. This could potentially lead to unauthorized access to sensitive data and system configurations (Red Hat).

The vulnerability can be exploited by using a JWT token with an empty shared secret. The authentication bypass occurs because the system does not properly validate the shared secret parameter in the bearer authentication process (GitHub Issue).

The vulnerability has been fixed in InfluxDB version 1.7.6 and later releases. The fix includes additional validation to fail bearer authentication if the shared secret is blank. Various Linux distributions have also released security updates, including Debian 9 (version 1.1.1+dfsg1-4+deb9u1) and Debian 10 (version 1.6.4-1+deb10u1) (Debian Security, Debian LTS).