An issue has been discovered in GitLab CE/EE affecting all versions before 17.10.7, 17.11 before 17.11.3, and 18.0 before 18.0.1. An attacker may be able to reveal masked or hidden CI variables (that they did not author) in the WebUI, by simply creating their own variable and observing the HTTP response.
The product implements access controls via a policy or other feature with the intention to disable or restrict accesses (reads and/or writes) to assets in a system from untrusted agents. However, implemented access controls lack required granularity, which renders the control policy too broad because it allows accesses from unauthorized agents to the security-sensitive assets.
Integrated circuits and hardware engines can expose accesses to assets (device configuration, keys, etc.) to trusted firmware or a software module (commonly set by BIOS/bootloader). This access is typically access-controlled. Upon a power reset, the hardware or system usually starts with default values in registers, and the trusted firmware (Boot firmware) configures the necessary access-control protection. A common weakness that can exist in such protection schemes is that access controls or policies are not granular enough. This condition allows agents beyond trusted agents to access assets and could lead to a loss of functionality or the ability to set up the device securely. This further results in security risks from leaked, sensitive, key material to modification of device configuration.