CVE-2026-49855
HIGHtornado AsyncHTTPClient accumulates decompressed chunks without size limit (gzip bomb)
Title source: cnaDescription
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.
References (3)
Core 3
Core References
X_Refsource_Confirm x_refsource_confirm
https://github.com/tornadoweb/tornado/security/advisories/GHSA-mgf9-4vpg-hj56
X_Refsource_Misc x_refsource_misc
https://github.com/tornadoweb/tornado/pull/3626
X_Refsource_Misc x_refsource_misc
https://github.com/tornadoweb/tornado/commit/ff808b33adc52d89a549376a5e3628e92abbc8ff
Scores
CVSS v3
7.5
EPSS
0.0057
EPSS Percentile
44.0%
Attack Vector
NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CISA SSVC
Vulnrichment
Exploitation
none
Automatable
yes
Technical Impact
partial
Details
CWE
CWE-409
Status
published
Products (1)
tornadoweb/tornado
< 6.5.6
Published
Jul 14, 2026
Tracked Since
Jul 15, 2026