Infinite loop in urllib3 - #VU150183
Published: September 16, 2026 / Updated: September 18, 2026
Vulnerability identifier: #VU150183
CSH Severity: Medium
CVSS v4: 6.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N]
CVE-ID: N/A
CWE-ID: CWE-835
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 a loop with an unreachable exit condition in the Deflate decoder when processing a chunked Deflate-encoded response containing bytes after the end of the compressed stream. A remote attacker can send a specially crafted response to cause a denial of service.
Exploitation requires content decoding to be enabled, streaming with a positive finite chunk size, and a decoded body that exceeds the requested chunk size.
Affected software
urllib3
Remediation
Install security update from vendor's website.
urllib3 - update to 2.8.0