{"schema_version": "1.6.1", "id": "CVE-2026-54428", "summary": "HPackDecoder Unlimited Header List Size Before SETTINGS ACK", "details": "Allocation of resources without limits or throttling in the HTTP/2 HPACK decoder in Apache HttpComponents Core (5.4.2 and earlier, 5.5-beta1 and earlier) allows an remote attacker to cause a denial of service through memory exhaustion by sending oversized compressed header blocks before the HTTP/2 SETTINGS acknowledgement causes the configured header list size limit to be applied.", "affected": [{"ranges": [{"type": "SEMVER", "events": [{"introduced": "5.5-alpha"}, {"last_affected": "5.5-alpha"}]}, {"type": "SEMVER", "events": [{"introduced": "5.0-alpha"}, {"last_affected": "5.0-alpha"}]}]}], "references": [{"type": "WEB", "url": "https://lists.apache.org/thread/5zjp8vczvxq19pw2rvhs21q446bhl0sd"}]}