High [CVE-2026-54770] Open redirect vulnerability leading to phishing and token theft

WebOb provides objects for HTTP requests and responses. Prior to 1.8.11, Response._make_location_absolute() in src/webob/response.py checks a Location value for a URI scheme or leading double slash before urllib.parse.urljoin() strips leading C0 control characters and spaces.

An attacker-controlled value such as a space followed by a protocol-relative or absolute URL can therefore bypass SCHEME_RE and startswith("//") checks and be normalized to an off-host redirect.

Request.relative_url() and webob.exc._HTTPMove subclasses, including HTTPFound, are also affected because they use the same unsafe URL joining behavior or bypass the earlier normalization path.

An unauthenticated attacker who can influence an application's redirect target can send users to an attacker-controlled host for phishing or OAuth and SSO token theft, but exploitation requires the user to follow the redirect. This issue is fixed in version 1.8.11.

This vulnerability allows an unauthenticated attacker to bypass URL validation checks by injecting leading control characters or spaces into a redirect target. This can lead to an open redirect, enabling attackers to send users to malicious websites for phishing or to steal OAuth and Single Sign-On (SSO) tokens.

Red Hat severity: Important — CVSS 7.4 (CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:N/A:N). Weakness: CWE-601.