# 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.

- **Severity:** Medium 6.1 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N`)
- **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:** Yes
- **Published:** 20 Aug 2026
- **Updated:** 25 Aug 2026
- **Also known as:** AZL-97575, DEBIAN-CVE-2026-54770, ECHO-89e1-36b7-43be, GHSA-6hx8-3wjj-gr8g, MINI-5p93-m7xx-77vp, PYSEC-2026-3943, SUSE-SU-2026:4351-1, SUSE-SU-2026:4765-1, UBUNTU-CVE-2026-54770, openSUSE-SU-2026:11864-1

## 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 (URL Redirection to Untrusted Site)

## Which versions are affected by CVE-2026-54770?

3 open source packages ship an affected version, including webob.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `webob` | PyPI | All versions | 1.8.11 |
| `webob` | PyPI | All versions | 1.8.11 |
| `webob` | PyPI | All versions | 1.8.11 |
| `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.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-54770 and fix it if it is affected.

What it is: 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.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-54770 exists.

Affected packages and fixed versions:
- webob (PyPI): affected all versions; fixed in 1.8.11
- webob (PyPI): affected all versions; fixed in 1.8.11
- webob (PyPI): affected all versions; fixed in 1.8.11

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-54770/ (Markdown: https://insights.sbomify.com/CVE-2026-54770/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-54770
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-54770
- OSV: https://osv.dev/vulnerability/CVE-2026-54770

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-54770/
Summaries are generated and may contain mistakes; the official description above is the record.