CVE-2026-44160: Fluentd is Vulnerable to Denial of Service (DoS) via Gzip Decompression Bomb in `in_http` and `in_forward`

Fluentd’s in_http and in_forward plugins support receiving gzip-compressed data. While Fluentd correctly enforces size limits on the incoming compressed payloads (e.g., via body_size_limit or chunk_size_limit), it was discovered that there is no limit enforced on the size of the decompressed data.

If a Fluentd instance is exposed to untrusted networks, an attacker can send a maliciously crafted, highly compressed payload. When Fluentd attempts to decompress this payload in memory, it will expand to an excessive size, completely bypassing the intended payload size limits.