The vulnerability in webob's Response._make_location_absolute() method involves insufficient normalization of Location header values before URL joining. Specifically, leading C0 control characters and spaces are stripped only after checks for URI scheme or leading double slashes, allowing crafted inputs to bypass these checks and cause an open redirect to an off-host URL. Other affected components include Request.relative_url() and webob.exc._HTTPMove subclasses such as HTTPFound, which use the same unsafe URL joining logic. An unauthenticated attacker who can influence redirect targets may exploit this to redirect users to malicious sites, potentially facilitating phishing or token theft. The issue is resolved in version 1.8.11.

An attacker can cause users to be redirected to attacker-controlled websites by exploiting the open redirect vulnerability. This can be used for phishing attacks or theft of OAuth and SSO tokens if users follow the malicious redirects. The vulnerability requires user interaction (following the redirect) and does not allow direct compromise of the affected system. The CVSS score is 6.1 (medium severity), reflecting network attack vector, low complexity, no privileges required, user interaction required, and partial confidentiality and integrity impact.

This vulnerability is fixed in webob version 1.8.11. Users should upgrade to version 1.8.11 or later to remediate this issue. No official patch or remediation level is explicitly stated beyond this fix. Until upgraded, applications should carefully validate and sanitize redirect targets to prevent open redirects.