Curl QUIC HTTP/3 UDP DoS from Empty Datagram Abuse
CVE-2026-11352 Published on July 3, 2026
QUIC zero-length UDP datagrams busy-loop
An issue in curls QUIC UDP receive function allows a malicious HTTP/3 server
to trigger a remote denial of service against a curl or libcurl client.
Because the helper function discards zero-length UDP datagrams before counting
them toward the per-call packet budget, a connected QUIC peer can continuously
stream empty datagrams to indefinitely stall the client.
Vulnerability Analysis
CVE-2026-11352 is exploitable with network access, and does not require authorization privileges or user interaction. This vulnerability is considered to have a low attack complexity. An automatable proof of concept (POC) exploit exists. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality and integrity, and a high impact on availability.
Weakness Type
What is an Infinite Loop Vulnerability?
The program contains an iteration or loop with an exit condition that cannot be reached, i.e., an infinite loop. If the loop can be influenced by an attacker, this weakness could allow attackers to consume excessive resources such as CPU or memory.
CVE-2026-11352 has been classified to as an Infinite Loop vulnerability or weakness.
Products Associated with CVE-2026-11352
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Affected Versions
curl:- Version 8.18.0 and below 8.20.1 is affected.
- Version 6a3d0b6d631d5e9bec797306b5b41a9f440a088d and below 56eca2afb4806f1032872fa97d1834b3c1385276 is affected.
- Version 8.20.0 is affected.
- Version 8.19.0 is affected.
- Version 8.18.0 is affected.
Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.