Remote denial of service via QUIC UDP receive function vulnerability

Summary

An issue in curl’s 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. 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. Red Hat severity: Important — CVSS 7.5 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H). Weakness: CWE-835. No fixing RHSA erratum has published yet; monitor the Red Hat CVE page and patch when it ships.