Description
In some circumstances, when DNSdist is configured to use the nghttp2 library to process incoming DNS over HTTPS queries, an attacker might be able to cause a denial of service by crafting a DoH exchange that triggers an unbounded I/O read loop, causing an unexpected consumption of CPU resources.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| PowerDNS | DNSdist | 1.9.0 – < 1.9.11, 2.0.0 – < 2.0.1 | 1.9.11 |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | dnsdist | 2.0.1-1 | — |
| Debian 13 | dnsdist | 1.9.10-1+deb13u1 | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 25.10 | dnsdist | 1.9.10-1ubuntu0.1 | USN-8037-1 |
Show 2 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 24.04 LTS | dnsdist | 1.8.3-2ubuntu0.1~esm1 | USN-8037-1 |
| Ubuntu Pro 22.04 LTS | dnsdist | 1.6.1-1ubuntu0.1~esm2 | USN-8037-1 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 15 SP7 | dnsdist | 1.9.11-150700.3.6.1 | SUSE-SU-2026:0888-1 |
Show 2 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES for SAP 16.0 | dnsdist | 1.9.11-160000.1.1 | SUSE-SU-2026:20995-1 |
| SLES 16.0 | dnsdist | 1.9.11-160000.1.1 | SUSE-SU-2026:20995-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Leap 16.0 | dnsdist | 1.9.11-160000.1.1 | openSUSE-SU-2026:20461-1 |
Alpine
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.24 | dnsdist | 2.0.1-r0 | — |
| Alpine v3.23 | dnsdist | 2.0.1-r0 | — |
Advisories 5
- USN-8037-1 dnsdist vulnerabilities Ubuntu Security Notices (USN) · Apr 27, 2026
- SUSE-SU-2026:20995-1 Security update for dnsdist SUSE / openSUSE Security Updates · Apr 10, 2026
- WID-SEC-2025-2112 DNSdist: Schwachstelle ermöglicht Denial of Service BSI CERT-Bund (WID) · Apr 9, 2026
- openSUSE-SU-2026:20461-1 Security update for dnsdist SUSE / openSUSE Security Updates · Apr 9, 2026
- SUSE-SU-2026:0888-1 Security update for dnsdist SUSE / openSUSE Security Updates · Mar 14, 2026