Quick answers
- Is CVE-2026-32665 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-32665 being exploited in the wild.
- How severe is CVE-2026-32665?
- High severity, with a CVSS score of 7.5, published 22 July 2026.
- Which products and versions are affected?
- NLnet Labs Unbound 1.22.0 through 1.25.1.
- Is there a fix for CVE-2026-32665?
- A patch was published on 2026-07-22: Fixed in Unbound 1.25.2 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
- How is CVE-2026-32665 attacked?
- It is attacked over the network, in a hosted service.
- Am I affected by CVE-2026-32665?
- Check whether you run NLnet Labs Unbound at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
Technical details
A vulnerability exists in Unbound's downstream DNS-over-QUIC (DoQ) implementation where the first two bidirectional streams (IDs 0 and 4) of a new connection bypass the 'quic-size' memory limit validation. An attacker can send a 2-byte length prefix declaring a large payload (up to 65535 bytes) without actually sending the data, forcing Unbound to allocate large input buffers prematurely. By maintaining these open streams, a remote unauthenticated attacker can exceed configured memory budgets with minimal effort, leading to a denial of service for subsequent DoQ clients. This issue affects Unbound versions 1.22.0 through 1.25.1 when compiled with 'libngtcp2' and configured with a 'quic-port'. The vulnerability is addressed in version 1.25.2.
Affected products
- NLnet Labs Unbound 1.22.0 through 1.25.1
Timeline
- 2026-07-22: disclosed
- 2026-07-22: advisory
- 2026-07-22: patched: Fixed in Unbound 1.25.2