CVE-2017-0356 Authentication bypass via repeated parameters

What is CVE-2017-0356?

CVE-2017-0356 is a critical authentication bypass vulnerability in Debian Debian Linux, published on 13 Apr 2018. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

A flaw, similar to to CVE-2016-9646, exists in ikiwiki before 3.20170111, in the passwordauth plugin's use of CGI::FormBuilder, allowing an attacker to bypass authentication via repeated parameters.

Weakness: CWE-287

Which versions are affected by CVE-2017-0356?

It affects 2 products.

Products include Debian Debian Linux, Ikiwiki Ikiwiki.

How do I fix CVE-2017-0356?

Upgrade to a fixed version.

Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.

Is CVE-2017-0356 being exploited?

There is no known exploitation of CVE-2017-0356 in the wild and no public exploit code.

Other vulnerabilities in Debian Debian Linux

• CVE-2015-3306 ProFTPD Improper Access Control Exploited Critical 10.0
• CVE-2025-49113 RoundCube Webmail Deserialization of Untrusted Data Exploited Critical 9.9
• CVE-2026-24061 GNU InetUtils Argument Injection Exploited Critical 9.8
• CVE-2025-39682 Linux Kernel Improper Check for Unusual or Exceptional Conditions Exploited Critical 9.8
• CVE-2024-9680 Mozilla Firefox Use-After-Free Exploited Critical 9.8

All Debian Debian Linux vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as DEBIAN-CVE-2017-0356, GHSA-v4mw-26wf-pfx6, UBUNTU-CVE-2017-0356.