# CVE-2021-32786: Open Redirect in oidc_validate_redirect_url()


- **Severity:** Medium 4.7 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Fix available:** Yes
- **Published:** 22 Jul 2021
- **Updated:** 3 Aug 2024
- **Also known as:** AZL-6480, DEBIAN-CVE-2021-32786, GHSA-xm4c-5wm5-jqv7, UBUNTU-CVE-2021-32786

## What is CVE-2021-32786?

CVE-2021-32786 is a medium-severity vulnerability in Fedoraproject Fedora, published on 22 Jul 2021. 

### Official description

mod_auth_openidc is an authentication/authorization module for the Apache 2.x HTTP server that functions as an OpenID Connect Relying Party, authenticating users against an OpenID Connect Provider. In versions prior to 2.4.9, `oidc_validate_redirect_url()` does not parse URLs the same way as most browsers do. As a result, this function can be bypassed and leads to an Open Redirect vulnerability in the logout functionality. This bug has been fixed in version 2.4.9 by replacing any backslash of the URL to redirect with slashes to address a particular breaking change between the different specifications (RFC2396 / RFC3986 and WHATWG). As a workaround, this vulnerability can be mitigated by configuring `mod_auth_openidc` to only allow redirection whose destination matches a given regular expression.

Weakness: CWE-601 (URL Redirection to Untrusted Site)

## Which versions are affected by CVE-2021-32786?

It affects 2 products.


Products: Fedoraproject Fedora, Openidc Mod Auth Openidc.

## How do I fix CVE-2021-32786?

Upgrade to a fixed version.

## Is CVE-2021-32786 being exploited?

There is no known exploitation of CVE-2021-32786 in the wild and no public exploit code.

## Other vulnerabilities in Fedoraproject Fedora

- [CVE-2024-4577](https://insights.sbomify.com/CVE-2024-4577/): PHP-CGI OS Command Injection (critical 9.8, exploited in the wild)
- [CVE-2021-39226](https://insights.sbomify.com/CVE-2021-39226/): Grafana Authentication Bypass (critical 9.8, exploited in the wild)
- [CVE-2019-5544](https://insights.sbomify.com/CVE-2019-5544/): VMware ESXi and Horizon DaaS OpenSLP Heap-Based Buffer Overflow (critical 9.8, exploited in the wild)
- [CVE-2024-4947](https://insights.sbomify.com/CVE-2024-4947/): Google Chromium V8 Type Confusion (critical 9.6, exploited in the wild)
- [CVE-2024-4671](https://insights.sbomify.com/CVE-2024-4671/): Google Chromium Visuals Use-After-Free (critical 9.6, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-32786 and fix it if it is affected.

What it is: CVE-2021-32786 is a medium-severity vulnerability in Fedoraproject Fedora, published on 22 Jul 2021. 
Exploitation: There is no known exploitation of CVE-2021-32786 in the wild and no public exploit code.

Affected product: Fedoraproject Fedora. No package-level version data is available, so check the vendor advisory linked from the reference page.

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-2021-32786/ (Markdown: https://insights.sbomify.com/CVE-2021-32786/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-32786
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-32786
- OSV: https://osv.dev/vulnerability/CVE-2021-32786

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-32786/
Summaries are generated and may contain mistakes; the official description above is the record.