# CVE-2021-3639: libapache2-mod-auth-mellon: A flaw was found in mod_auth_mellon where it does not sanitize logout URLsproperly

CVE-2021-3639 is fixed in 3 products on 1 platform, first by libapache2-mod-auth-mellon 0.13.1-1ubuntu0.3, released August 3, 2021. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2021-3639
- Priority: Routine
- CVSS: 6.1 (Medium)
- EPSS: 0.0106
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Aug 3, 2021

## Description

A flaw was found in mod_auth_mellon where it does not sanitize logout URLsproperly. This issue could be used by an attacker to facilitate phishingattacks by tricking users into visiting a trusted web application URL thatredirects to an external and potentially malicious server. The highestthreat from this liability is to confidentiality and integrity.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | libapache2-mod-auth-mellon Debian 12.15 (bookworm) | 0.18.0-1 | [DEBIAN-CVE-2021-3639](https://patchblox.com/security/data/fix/linux/debian-cve-2021-3639.md) | Aug 22, 2022 |
| Linux | libapache2-mod-auth-mellon Debian 13.5 (trixie) | 0.18.0-1 | [DEBIAN-CVE-2021-3639](https://patchblox.com/security/data/fix/linux/debian-cve-2021-3639.md) | Aug 22, 2022 |
| Linux | libapache2-mod-auth-mellon Debian 14 | 0.18.0-1 | [DEBIAN-CVE-2021-3639](https://patchblox.com/security/data/fix/linux/debian-cve-2021-3639.md) | Aug 22, 2022 |
| Linux | libapache2-mod-auth-mellon Ubuntu 18.04.6 LTS (bionic) | 0.13.1-1ubuntu0.3 | [libapache2-mod-auth-mellon 0.13.1-1ubuntu0.3](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-libapache2-mod-auth-mellon-0.13.1-1ubuntu0.3.md) | Aug 3, 2021 |
| Linux | libapache2-mod-auth-mellon Ubuntu 20.04 LTS (focal) | 0.16.0-1ubuntu0.1 | [libapache2-mod-auth-mellon 0.16.0-1ubuntu0.1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-libapache2-mod-auth-mellon-0.16.0-1ubuntu0.1.md) | Aug 3, 2021 |
| Linux | libapache2-mod-auth-mellon Ubuntu 22.04.1 LTS (jammy) | 0.17.0-1ubuntu1 | [libapache2-mod-auth-mellon 0.17.0-1ubuntu1](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-libapache2-mod-auth-mellon-0.17.0-1ubuntu1.md) | Aug 3, 2021 |
| Linux | libapache2-mod-auth-mellon Ubuntu 24.10 (oracular) | 0.17.0-1ubuntu1 | [libapache2-mod-auth-mellon 0.17.0-1ubuntu1](https://patchblox.com/security/data/fix/linux/ubuntu-oracular-libapache2-mod-auth-mellon-0.17.0-1ubuntu1.md) | Jan 16, 2026 |
| Linux | libapache2-mod-auth-mellon Ubuntu 25.04 (plucky) | 0.17.0-1ubuntu1 | [libapache2-mod-auth-mellon 0.17.0-1ubuntu1](https://patchblox.com/security/data/fix/linux/ubuntu-plucky-libapache2-mod-auth-mellon-0.17.0-1ubuntu1.md) | Jan 16, 2026 |
| Linux | mod_auth_mellon RHEL 8 | 0:0.14.0-12.el8.1 | [RHSA-2022:1934](https://patchblox.com/security/data/fix/linux/rhsa-2022-1934.md) | May 10, 2022 |
| Linux | mod_auth_mellon almalinux 8 | 0.14.0-12.el8.1 | [ALSA-2022:1934](https://patchblox.com/security/data/fix/linux/alsa-2022-1934.md) | May 10, 2022 |
| Linux | mod_auth_mellon ol 8 | 0:0.14.0-12.el8.1 | [ELSA-2022-1934](https://patchblox.com/security/data/fix/linux/elsa-2022-1934.md) | May 17, 2022 |
| Linux | mod_auth_mellon rocky 8 | 0:0.14.0-12.el8.1 | [RLSA-2022:1934](https://patchblox.com/security/data/fix/linux/rlsa-2022-1934.md) | May 10, 2022 |
| Linux | mod_auth_mellon-diagnostics RHEL 8 | 0:0.14.0-12.el8.1 | [RHSA-2022:1934](https://patchblox.com/security/data/fix/linux/rhsa-2022-1934.md) | May 10, 2022 |
| Linux | mod_auth_mellon-diagnostics almalinux 8 | 0.14.0-12.el8.1 | [ALSA-2022:1934](https://patchblox.com/security/data/fix/linux/alsa-2022-1934.md) | May 10, 2022 |
| Linux | mod_auth_mellon-diagnostics ol 8 | 0:0.14.0-12.el8.1 | [ELSA-2022-1934](https://patchblox.com/security/data/fix/linux/elsa-2022-1934.md) | May 17, 2022 |

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