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.
| Product | Vendor Advisory | Solution File | Added | Published |
|---|---|---|---|---|
| Alpine Linux | — | Upgrade dnsdist | Aug 8, 2025 | Apr 29, 2025 |
| Debian | — | Upgrade dnsdist | Jul 23, 2026 | Jul 23, 2026 |
| Freebsd | — | Upgrade null | May 5, 2025 | May 4, 2025 |
| Suse | — | Upgrade dnsdist | Dec 5, 2025 | May 29, 2025 |
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