CVE-2026-54770 WebOb: Open redirect in Location header normalization via leading C0 control / space characters
An attacker can bypass redirect validation to send users to malicious sites, enabling phishing or token theft in applications using WebOb.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-54770?
CVE-2026-54770 is a medium-severity vulnerability in Pylons webob, published on 20 Aug 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official description
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.
Weakness: CWE-601
Which versions are affected by CVE-2026-54770?
3 open source packages ship an affected version, including webob.
| Package | Affected | Fixed in |
|---|---|---|
webob PyPI | All versions | 1.8.11 |
webob PyPI | All versions | 1.8.11 |
webob PyPI | All versions | 1.8.11 |
Linux distribution packages (4)
python-WebOb SUSE:Linux Enterprise Module for Basesystem 15 SP7 | All versions | 1.7.4-150000.3.9.1 |
python-WebOb SUSE:Linux Enterprise Module for Package Hub 15 SP7 | All versions | 1.7.4-150000.3.9.1 |
python-WebOb SUSE:Linux Enterprise Module for Public Cloud 12 | All versions | 1.2.3-3.6.1 |
python-WebOb openSUSE:Tumbleweed | All versions | 1.8.11-1.1 |
How do I fix CVE-2026-54770?
Upgrade webob to 1.8.11 or later.
Is CVE-2026-54770 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-54770 exists.
Sources
Also known as AZL-97575, DEBIAN-CVE-2026-54770, ECHO-89e1-36b7-43be, GHSA-6hx8-3wjj-gr8g, MINI-5p93-m7xx-77vp, PYSEC-2026-3943 and 4 more.