CVE-2026-5366: Prefect

Critical severity, CVSS 9.9. EPSS: 1% chance of exploitation in the next 30 days.

Prefect version 3.6.23 is vulnerable to remote code execution due to improper handling of user-controlled input in the `GitRepository` storage class. The `commit_sha` parameter, which is passed to git commands, lacks validation and does not include a `--` separator to distinguish user input from git flags. This allows attackers to inject arbitrary git flags, such as `--upload-pack`, enabling execution of external programs. Additionally, the `directories` parameter can be exploited to inject git flags during sparse-checkout operations. These vulnerabilities allow any user with deployment creation permissions to execute arbitrary commands on worker machines, compromising shared work pools in multi-tenant environments.

Affected products

• Prefect Prefect: version 3.6.23 only

Published 2026-06-20. Last modified 2026-07-01.