CVE detail
CVE-2026-32665
In NLnet Labs Unbound 1.22.0 up to and including 1.25.1, when downstream DNS-over-QUIC (DoQ) is enabled, the first two bidirectional streams on a new QUIC connection (stream_id 0 and 4) bypass the per-stream 'quic-size' gate entirely, and large input buffers are allocated later, after only the 2-byte length prefix has been received from the initial streams. As a result, a remote client can make Unbound exceed the configured 'quic-size' limit with low-cost input. Using only one connection and two streams, each sending a declared 65535-byte length prefix and then holding the streams open, a client can already trivially make Unbound roughly allocate double that amount. This is a remote availability issue / memory-accounting bypass in the downstream DoQ implementation that leads to denial of service for new DoQ clients. This vulnerability needs Unbound to be compiled with DoQ support ('--with-libngtcp2') and the 'quic-port' to be configured for the listening interfaces.
Buzz score
Why this CVE is surfacing
This all-time snapshot uses the same composite formula as Trending across a 30-year evidence window, rather than a current rolling window.
Buzz score components · mention 11.0 · diversity 10.0 · KEV 0.0 · OTX 0.0 · PoC 0.0
Why it matters now
Mention timeline
- Total mentions
- 2
- within the 30d window
- Peak daily
- 1
- highest bucket
Evidence
Source links by recency
2 source links · newest first
- CVE-2026-32665 Remote DNS-over-QUIC denial of service due to `quic-size` budget bypassMicrosoft MSRC
Information published.
vendormsrc.microsoft.comJul 23, 2026, 8:04 AM - https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-32665.txtwww.nlnetlabs.nl
No excerpt available.
Vendor Advisorywww.nlnetlabs.nlJul 22, 2026, 2:17 PM
Exploit code
Public exploit repository references
Public PoC repositories are third-party, potentially unsafe artifacts. Treat their code as untrusted and use it only on authorized systems in an isolated, least-privilege environment. cvebuzz does not execute the code or verify that an exploit works.
0 repository references · best confidence N/A · max 0 stars
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