Time-of-check Time-of-use (TOCTOU) Race Condition Affecting prefect package, versions [,3.6.28.dev2)
Threat Intelligence
Snyk has a proof-of-concept or detailed explanation of how to exploit this vulnerability.
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
Do your applications use this vulnerable package?
In a few clicks we can analyze your entire application and see what components are vulnerable in your application, and suggest you quick fixes.
Test your applicationsSnyk Learn
Learn about Time-of-check Time-of-use (TOCTOU) Race Condition vulnerabilities in an interactive lesson.
Start learning- Snyk IDSNYK-PYTHON-PREFECT-16383760
- published4 May 2026
- disclosed4 May 2026
- creditnedlir
Introduced: 4 May 2026
NewCVE-2026-7724 (opens in a new tab)How to fix?
Upgrade prefect to version 3.6.28.dev2 or higher.
Overview
prefect is a Prefect is a new workflow management system, designed for modern infrastructure and powered by the open-source Prefect Core workflow engine. Users organize Tasks into Flows, and Prefect takes care of the rest.
Affected versions of this package are vulnerable to Time-of-check Time-of-use (TOCTOU) Race Condition in the validate_restricted_url() function of the Webhook and CustomWebhookNotificationBlock components, which enables DNS rebinding attacks. When allow_private_urls is set to False, an attacker can bypass intended URL restrictions by returning a public IP address first, which passes validation, and then a private one at the time of the actual connection.