GitHub has released security updates for Enterprise Server (GHES) to address multiple issues, including a critical bug that could allow unauthorized access to an instance.

The vulnerability, tracked as CVE-2024-9487, carries a CVS score of 9.5 out of a maximum of 10.0

"An attacker could bypass SAML single sign-on (SSO) authentication with the optional encrypted assertions feature, allowing unauthorized provisioning of users and access to the instance, by exploiting an improper verification of cryptographic signatures vulnerability in GitHub Enterprise Server," GitHub said in an alert.

The Microsoft-owned company characterized the flaw as a regression that was introduced as part of follow-up remediation from CVE-2024-4985 (CVSS score: 10.0), a maximum severity vulnerability that was patched back in May 2024.

Also fixed by GitHub are two other shortcomings -

• CVE-2024-9539 (CVSS score: 5.7) - An information disclosure vulnerability that could enable an attacker to retrieve metadata belonging to a victim user upon clicking malicious URLs for SVG assets

• A sensitive data exposure in HTML forms in the management console (no CVE)

All three security vulnerabilities have been addressed in Enterprise Server versions 3.14.2, 3.13.5, 3.12.10, and 3.11.16.

Back in August, GitHub also patched a critical security defect (CVE-2024-6800, CVSS score: 9.5) that could be abused to gain site administrator privileges.

Organizations that are running a vulnerable self-hosted version of GHES are highly advised to update to the latest version to safeguard against potential security threats.