Zero-length DATAGRAM frames bypass the receive buffer limit in quinn-proto

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

quinn-proto bounds its queue of received datagrams by charging each queued frame's payload length against `TransportConfig::datagram_receive_buffer_size`, evicting the oldest datagrams when the limit is exceeded. A DATAGRAM frame with an empty payload was charged zero bytes, so it never triggered eviction and was appended to the queue, which has no other bound. DATAGRAM frames are not subject to flow control. A peer that has completed the handshake can therefore send a stream of empty DATAGRAM frames and grow the receiver's heap without limit until the process is killed. An application that reads incoming datagrams but does so more slowly than the peer sends them is still affected. Receiving datagrams is enabled by default, so all endpoints that do not explicitly set `datagram_receive_buffer_size(None)` are affected. The send path had the same accounting flaw: an application could enqueue an unbounded number of empty outgoing datagrams without ever receiving `SendDatagramError::Blocked`. The flaw was corrected in 0.11.17 by accounting for the fixed per-datagram overhead in both directions, so that every queued datagram consumes buffer space. Thanks to [@alexpyattaev](https://github.com/alexpyattaev) for reporting this issue.

Source published

17 Aug 2026 12:00:00 UTC

Source modified

12 Oct 2026 18:15:01 UTC

Observed here

24 Oct 2026 13:19:54 UTC

Source terms

OSV · upstream source license applies

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · OSV · upstream source license applies. Source text is retained; field grouping and change labels are provided by ChangeIntel.