CVE-2026-49855
tornado AsyncHTTPClient accumulates decompressed chunks without size limit (gzip bomb)
CVSS Score
7.5
EPSS Score
0.0%
EPSS Percentile
0th
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.
| CWE | CWE-409 |
| Vendor | tornadoweb |
| Product | tornado |
| Published | Jul 14, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High
Affected Versions
tornadoweb / tornado
< 6.5.6