CVE-2021-32786
Open Redirect in oidc_validate_redirect_url()
Reported by github_m · Published July 22, 2021
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.
Fixed versions
Upgrade to a fixed version or later. Language registries are listed first, then Linux distributions, then vendor products.
| Package | Ecosystem | Fixed in |
|---|---|---|
| mod_auth_openidc | openidc | 2.4.9 |
Risk scores
Affected products
| Vendor | Product | Versions |
|---|---|---|
| zmartzone | mod_auth_openidc | < 2.4.9 |
| zmartzone | mod_auth_openidc | 0 |
Timeline
- Jul 22, 2021 CVE Published
- Jul 23, 2021 EPSS Score (30 in total, the first dated here)
- Aug 3, 2024 CVE Updated
- Mar 21, 2026 Security Advisory (4 in total, the first dated here)
- Mar 21, 2026 Distribution Patch
- Aug 1, 2026 Coalition ESS Score
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References
- FEDORA-2021-e3017c538a vendor-advisory
- FEDORA-2021-17f5cedf66 vendor-advisory
- [debian-lts-announce] 20230430 [SECURITY] [DLA 3409-1] libapache2-mod-auth-openidc security update mailing-list