curl vulnerability

What happened

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.

Affected versions

curl: 8.18.0 through before 8.20.1 (semver); 6a3d0b6d631d5e9bec797306b5b41a9f440a088d through before 56eca2afb4806f1032872fa97d1834b3c1385276 (git); 8.20.0; 8.19.0; 8.18.0 Fixed: See vendor advisory.

Why it matters

Review the vendor advisory and exposure of the affected product to determine operational impact.

Detection & mitigation

• Apply vendor-provided updates or mitigations.
• Review affected product exposure and access logs.