A now-patched critical remote code execution vulnerability in GitLab’s web interface has been detected as actively exploited in the wild, cybersecurity researchers warn, rendering a large number of internet-facing GitLab instances susceptible to attacks.

The vulnerability, which affects all versions starting from 11.9, has since been addressed by GitLab on April 14, 2021 in versions 13.8.8, 13.9.6, and 13.10.3.

In one of the real-world attacks detailed by HN Security last month, two user accounts with admin privileges were registered on a publicly-accessible GitLab server belonging to an unnamed customer by exploiting the aforementioned flaw to upload a malicious payload that leads to remote execution of arbitrary commands, including obtaining elevated permissions.

Despite the public availability of the patches for more than six months, of the 60,000 internet-facing GitLab installations, only 21% of the instances are said to be fully patched against the issue, with another 50% still vulnerable to RCE attacks.

In the light of the unauthenticated nature of this vulnerability, exploitation activity is expected to increase, making it critical that GitLab users update to the latest version as soon as possible.

Ideally, GitLab should not be an internet facing service,” the researchers said.