CVE-2026-49855
tornado AsyncHTTPClient accumulates decompressed chunks without size limit (gzip bomb)
- State
- Published
- Severity
- 7.5 High
- Published
- Jul 14, 2026
- Updated
- Jul 16, 2026
- Reserved
- Jun 1, 2026
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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 3.1 | 7.5 High | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H | GitHub_M |
Weaknesses
- CWE-409 Improper Handling of Highly Compressed Data (Data Amplification)
Affected Products
| Product | Versions |
|---|---|
tornadotornadoweb |
|
References
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