CVE-2026-49855 | THREATINT

Description

Tornado is a Python web framework and asynchronous networking library. Prior to 6.5.6, Tornado gzip decompression routines processed limited-size chunks but did not enforce an overall limit on accumulated decompressed chunks, allowing a malicious server accessed by SimpleAsyncHTTPClient or an HTTPServer configured with decompress_request=True to consume effectively unlimited memory. This issue is fixed in version 6.5.6.

PUBLISHED Reserved 2026-06-01 | Published 2026-07-14 | Updated 2026-07-14 | Assigner GitHub_M

HIGH: 7.5CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Problem types

CWE-409: Improper Handling of Highly Compressed Data (Data Amplification)

Product status

< 6.5.6

affected

References

github.com/...ornado/security/advisories/GHSA-mgf9-4vpg-hj56

github.com/tornadoweb/tornado/pull/3626

github.com/...ommit/ff808b33adc52d89a549376a5e3628e92abbc8ff

cve.org (CVE-2026-49855)

nvd.nist.gov (CVE-2026-49855)

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