CVE Feed

    Dashboard / CVE / CVE-2021-32786

    CVE-2021-32786

    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.

    Published:Jul 22, 2021
    Last Modified:Nov 21, 2024
    EPS:Jul 22, 2021
    EPSS Score:0.00088
    CVSS Score:4.7

    Affected Products

    Vendor
    Apache
    Product
    Http Server
    Vendor
    Fedoraproject
    Product
    Fedora
    Vendor
    Openidc
    Product
    Mod Auth Openidc
    Vendor
    Redhat
    Product
    Enterprise Linux

    Exploits

    https://daniel.haxx.se/blog/2017/01/30/one-url-standard-please/https://daniel.haxx.se/blog/2017/01/30/one-url-standard-please/

    Common Attack Pattern Enumeration and Classification (CAPEC)

    CAPEC-178 Cross-Site Flashing

    Related CVEs

    CVE-2026-48913 (CVSS 7.3) — Use After Free vulnerability in Apache HTTP Server module mod_http2 when file handles are already exhausted. …
    CVE-2026-42536 (CVSS 7.5) — Heap-based Buffer Overflow vulnerability in Apache HTTP Server with mod_xml2enc, xml2StartParse, and untrusted…
    CVE-2026-44185 (CVSS 7.3) — Buffer Over-read vulnerability in Apache HTTP Server via outbound OCSP requests to an attacker controlled OCSP…
    CVE-2026-34355 (CVSS 7.5) — A buffer overflow in mod_proxy_html in Apache HTTP Server 2.4.67 and earlier allows an attack by an untrusted …
    CVE-2026-44631 (CVSS 9.8) — Buffer Underwrite vulnerability in Apache HTTP Server on crafted regular expressions in the configuration. Th…
    CVE-2026-44119 (CVSS 5.5) — Improper Privilege Management vulnerability in Apache HTTP Server 2.4.67 and earlier allows local .htaccess au…
    CVE-2026-43951 (CVSS 6.5) — Out-of-bounds Read vulnerability in Apache HTTP Server with mod_headers and mod_mime and multiple response lan…
    CVE-2026-42535 (CVSS 9.1) — A path handling issue in mod_dav_fs in Apache 2.4.67 and earlier allows a WebDAV content author to directly ma…
    CVE-2026-34356 (CVSS 7.5) — Heap-based Buffer Overflow vulnerability in Apache HTTP Server with malicious backend servers and ProxyPassRev…
    CVE-2026-44186 (CVSS 7.3) — Loop with Unreachable Exit Condition ('Infinite Loop') vulnerability in the mod_proxy_ftp module in Apache HTT…

    References

    https://daniel.haxx.se/blog/2017/01/30/one-url-standard-please/
    https://github.com/zmartzone/mod_auth_openidc/commit/3a115484eb927bc6daa5737dd84f88ff4bbc5544
    https://github.com/zmartzone/mod_auth_openidc/releases/tag/v2.4.9
    https://github.com/zmartzone/mod_auth_openidc/security/advisories/GHSA-xm4c-5wm5-jqv7
    https://lists.debian.org/debian-lts-announce/2023/04/msg00034.html
    https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/FZVF6BSJLRQZ7PFFR4X5JSU6KUJYNOCU/
    https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/QXAWKPT5LXZSUTFSJ6IWSZC7RMYYQXQD/
    https://security.netapp.com/advisory/ntap-20210902-0001/
    https://www.oracle.com/security-alerts/cpuapr2022.html
    https://daniel.haxx.se/blog/2017/01/30/one-url-standard-please/
    https://github.com/zmartzone/mod_auth_openidc/commit/3a115484eb927bc6daa5737dd84f88ff4bbc5544
    https://github.com/zmartzone/mod_auth_openidc/releases/tag/v2.4.9
    https://github.com/zmartzone/mod_auth_openidc/security/advisories/GHSA-xm4c-5wm5-jqv7
    https://lists.debian.org/debian-lts-announce/2023/04/msg00034.html
    https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/FZVF6BSJLRQZ7PFFR4X5JSU6KUJYNOCU/
    https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/QXAWKPT5LXZSUTFSJ6IWSZC7RMYYQXQD/
    https://security.netapp.com/advisory/ntap-20210902-0001/
    https://www.oracle.com/security-alerts/cpuapr2022.html

    Common Vulnerability Scoring System

    Attack Vector
    Network
    Adjacent
    Local
    Physical
    Privileges Required
    None
    Low
    High
    User Interaction
    None
    Required
    Scope
    Unchanged
    Changed
    Confidentiality
    None
    Low
    High
    Integrity
    None
    Low
    High
    Availability
    None
    Low
    High