CVE-2020-8159 Arbitrary file write in actionpack-page_caching gem

What is CVE-2020-8159?

CVE-2020-8159 is a critical path traversal vulnerability in Debian Debian Linux, published on 12 May 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

There is a vulnerability in actionpack_page-caching gem < v1.2.1 that allows an attacker to write arbitrary files to a web server, potentially resulting in remote code execution if the attacker can write unescaped ERB to a view.

Weakness: CWE-22

Which versions are affected by CVE-2020-8159?

2 open source packages ship an affected version, including actionpack-page_caching. It affects 2 products.

Products include Debian Debian Linux, Rubyonrails Actionpack Page-Caching.

How do I fix CVE-2020-8159?

Upgrade actionpack-page_caching to 1.2.1 or later.

Upgrade, and resolve every user-supplied path against an allowed base folder before opening it. More about Path traversal.

Is CVE-2020-8159 being exploited?

There is no known exploitation of CVE-2020-8159 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-2020-8159, DLA-2719-1, GHSA-mg5p-95m9-rmfp, UBUNTU-CVE-2020-8159.