Improper handling of highly compressed data in Tornado - #VU149941
Published: September 15, 2026
Vulnerability identifier: #VU149941
CSH Severity: Medium
CVSS v4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: N/A
CWE-ID: CWE-409
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to improper handling of highly compressed data in tornado.curl_httpclient.CurlAsyncHTTPClient when processing a gzip-compressed response from an attacker-controlled URL. A remote attacker can serve a decompression bomb to cause a denial of service.
The issue affects applications configured to use the curl HTTP client.
Affected software
Tornado
Remediation
Install security update from vendor's website.
Tornado - update to 6.5.9