# CVE-2026-54770: WebOb: Open redirect in Location header normalization via leading C0 control / space characters

CVE-2026-54770 is fixed in 2 products on 1 platform, first by DEBIAN-CVE-2026-54770, released August 20, 2026. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2026-54770
- Priority: Routine
- CVSS: 6.1 (Moderate)
- EPSS: 0.0042
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Aug 20, 2026
- Weakness: URL Redirection to Untrusted Site ('Open Redirect')
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-54770

## 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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | python-WebOb sles 15.7 | 1.7.4-150000.3.9.1 | [SUSE-SU-2026:4765-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4765-1.md) | Nov 7, 2026 |
| Linux | python-webob Debian 14 | 1:1.8.11-1 | [DEBIAN-CVE-2026-54770](https://patchblox.com/security/data/fix/linux/debian-cve-2026-54770.md) | Aug 20, 2026 |

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Data as of 2026-11-09T13:31:49Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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