Tornado: Event loop blocking and excess memory use from chunked bodies with many small chunks

影響: pip:tornado < 6.6 → 6.6

When Tornado reads an HTTP/1.1 body that uses chunked transfer encoding, it processes all chunks that have already arrived without yielding to the event loop. A client can send a body made of millions of 1-byte chunks, which blocks the event loop (and therefore every other connection served by that process) for the entire time it takes to parse the body. A body near the default max_body_size of 100 MB can block the process for close to a minute, and the attacker can repeat or parallelize these…

Read on GitHub Advisory Database

On 10/29/2026, 07:43 AM, GitHub Advisory Database published "Tornado: Event loop blocking and excess memory use from chunked bodies with many small chunks" (type: Advisory). Severity is "Medium" (medium). Related technologies: Python. CVE: CVE-2026-115927.