CVE-2026-11352

A flaw was found in curl and libcurl. A malicious HTTP/3 server can exploit an issue in the QUIC UDP receive function by continuously streaming empty UDP datagrams. This can lead to a remote denial of service (DoS) against a curl or libcurl client, as the helper function discards zero-length UDP datagrams before counting them toward the per-call packet budget, causing the client to indefinitely stall.

This Important flaw in curl and libcurl allows a remote malicious HTTP/3 server to trigger a denial of service against a client. By continuously sending zero-length UDP datagrams, an attacker can indefinitely stall the client, impacting service availability without requiring authentication or user interaction. This poses a significant risk to applications relying on curl for HTTP/3 communication.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.