CVE-2026-97687

urllib3 is an HTTP client library for Python. From 1.26.0 until 2.8.0, the proxy_ssl_context, proxy_assert_hostname, proxy_assert_fingerprint, ssl_context, cert_reqs, verify_mode, use_forwarding_for_https=True, and CERT_NONE configuration paths fail to remain separated because target-server TLS settings are incorrectly applied to the HTTPS proxy connection. The trigger is that an application uses an HTTPS proxy and configures target-server TLS settings that must remain separate from the proxy TLS handshake, including HTTPS forwarding with target-specific identity or credentials. Applying cert_reqs=CERT_NONE can overwrite proxy_ssl_context.verify_mode in place, and the mutation persists so later connections reusing the same context may connect to the HTTPS proxy without certificate verification. The attack mechanism is that an attacker intercepts and impersonates the HTTPS proxy after the effective proxy policy accepts the attacker's certificate. The impact is that the attacker can observe or modify forwarded traffic or receive a target TLS client certificate, while CONNECT tunneling still preserves the separate end-to-end target TLS connection. This issue is fixed in version 2.8.0.
Configurations

Configuration 1 (hide)

cpe:2.3:a:python:urllib3:*:*:*:*:*:*:*:*

History

13 Oct 2026, 20:27

Type Values Removed Values Added
CVSS v2 : unknown
v3 : unknown
v2 : unknown
v3 : 8.1
References () https://github.com/urllib3/urllib3/commit/07408cec79d1856d81bb42c74a904a24fdb9e465 - () https://github.com/urllib3/urllib3/commit/07408cec79d1856d81bb42c74a904a24fdb9e465 - Patch
References () https://github.com/urllib3/urllib3/commit/b6447295fff7b38fdffc67e0df9712d60cef3cc3 - () https://github.com/urllib3/urllib3/commit/b6447295fff7b38fdffc67e0df9712d60cef3cc3 - Patch
References () https://github.com/urllib3/urllib3/pull/5093 - () https://github.com/urllib3/urllib3/pull/5093 - Issue Tracking, Patch
References () https://github.com/urllib3/urllib3/releases/tag/2.8.0 - () https://github.com/urllib3/urllib3/releases/tag/2.8.0 - Release Notes
References () https://github.com/urllib3/urllib3/security/advisories/GHSA-8988-9cw3-xx77 - () https://github.com/urllib3/urllib3/security/advisories/GHSA-8988-9cw3-xx77 - Vendor Advisory
CPE cpe:2.3:a:python:urllib3:*:*:*:*:*:*:*:*
First Time Python urllib3
Python

29 Sep 2026, 16:17

Type Values Removed Values Added
New CVE

Information

Published : 2026-09-29 16:17

Updated : 2026-10-13 20:27


NVD link : CVE-2026-97687

Mitre link : CVE-2026-97687

CVE.ORG link : CVE-2026-97687


JSON object : View

Products Affected

python

  • urllib3
CWE
CWE-295

Improper Certificate Validation

CWE-440

Expected Behavior Violation