CVE-2026-49855

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.

CVSS v3 7.5 HIGH

7.5^/10

CVSS v3 : HIGH

Vector :

Exploitability : 3.9 / Impact : 3.6

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact NONE

Integrity Impact NONE

Availability Impact HIGH

Scope UNCHANGED

References

Link	Resource
https://github.com/tornadoweb/tornado/commit/ff808b33adc52d89a549376a5e3628e92abbc8ff
https://github.com/tornadoweb/tornado/pull/3626
https://github.com/tornadoweb/tornado/security/advisories/GHSA-mgf9-4vpg-hj56

Configurations

No configuration.

History

24 Oct 2026, 21:10

Type	Values Removed	Values Added
Summary		(es) Tornado es un framework web de Python y una biblioteca de red asíncrona. Antes de la versión 6.5.6, las rutinas de descompresión gzip de Tornado procesaban fragmentos de tamaño limitado pero no aplicaban un límite general a los fragmentos descomprimidos acumulados, lo que permitía a un servidor malicioso accedido por SimpleAsyncHTTPClient o un HTTPServer configurado con decompress_request=True consumir memoria de forma efectivamente ilimitada. Este problema está solucionado en la versión 6.5.6.

Information

Published : 2026-07-14 21:17

Updated : 2026-10-24 21:10

NVD link : CVE-2026-49855

Mitre link : CVE-2026-49855

CVE.ORG link : CVE-2026-49855

JSON object : View

Products Affected

No product.

CWE

CWE-409

Improper Handling of Highly Compressed Data (Data Amplification)

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