Threat database

CVE-2026-54770 is an open redirect vulnerability in the Pylons webob library prior to version 1.8.11. The issue arises from improper handling of Location header values in HTTP responses, allowing attacker-controlled input to bypass URL scheme checks and cause redirects to untrusted external sites. Exploitation requires user interaction by following the malicious redirect. The vulnerability is fixed in webob version 1.8.11.

WebOb provides objects for HTTP requests and responses. Prior to 1.8.10, the normalization of the HTTP Location header during a redirect is vulnerable to an open redirect: WebOb joins the redirect target to the request URI using Python's urljoin, and since Python 3.10 the underlying urlsplit strips ASCII tab, carriage return, and newline characters before parsing, so a redirect target containing such characters can be reinterpreted as a protocol-relative URL whose authority is an attacker-controlled host. This bypasses the CVE-2024-42353 fix that escaped a leading double slash, allowing an attacker who influences the redirect location to send users to an arbitrary external site instead of the intended one. This vulnerability is fixed in 1.8.10.