Tornado versions before 6.5.9 contain an unbounded memory accumulation vulnerability in CurlAsyncHTTPClient that allows remote attackers to cause denial of service by sending a compressed response. Attackers can send a gzip-encoded decompression bomb that accumulates in memory without size limits, causing the application process to be killed by out-of-memory conditions.
Weakness
The product does not handle or incorrectly handles a compressed input with a very high compression ratio that produces a large output.
References
- https://github.com/tornadoweb/tornado/commit/e412435febba4569c552c5c9054f1bf92bd171a9
- https://github.com/tornadoweb/tornado/security/advisories/GHSA-chx6-46f5-w4vp
- https://www.vulncheck.com/advisories/tornado-before-6.5.9-denial-of-service-via-curlasynchttpclient
- https://github.com/tornadoweb/tornado/security/advisories/GHSA-chx6-46f5-w4vp