CVE-2020-8159

Arbitrary file write in actionpack-page_caching gem

9.8 CriticalFix available

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.

Attack profile

How easy it is to exploit

Attack vector: Network
Complexity: Low
Privileges needed: None
User interaction: None

What an attacker can affect

Confidentiality: High
Integrity: High
Availability: High

Exploit likelihood

5.38%Up 4.4 points since Apr 14, 2021

What each source reports

NVD Score used 9.8

Record: CVE-2020-8159
CVSS 3.1: 9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CVSS 2.0: 7.5 HighAV:N/AC:L/Au:N/C:P/I:P/A:P
Weakness: CWE-22
Updated: 2026-11-02

CVE List No score

Record: CVE-2020-8159
Weakness: CWE-22
Updated: 2026-11-02

EUVDEUVD-2020-0432 No score

Record: EUVD-2020-0432
Updated: 2026-11-03

GitHub AdvisoriesGHSA-mg5p-95m9-rmfp 9.8

Arbitrary file write in actionpack-page_caching gem

Record: GHSA-mg5p-95m9-rmfp
CVSS 3.1: 9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness: CWE-22
Updated: 2026-11-02

OSV 9.8

Record: CVE-2020-8159
CVSS 3.1: 9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Updated: 2026-11-02

OSVDEBIAN-CVE-2020-8159 9.8

Record: DEBIAN-CVE-2020-8159
CVSS 3.1: 9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Updated: 2026-11-02

OSVGHSA-mg5p-95m9-rmfp 9.8

Arbitrary file write in actionpack-page_caching gem

Record: GHSA-mg5p-95m9-rmfp
CVSS 3.1: 9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness: CWE-22
Updated: 2026-11-02

OSVUBUNTU-CVE-2020-8159 9.8

Record: UBUNTU-CVE-2020-8159
CVSS 3.1: 9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Updated: 2026-11-02

Affected products

Affected packages

Affected packages
Package	Affected	Fixed
`actionpack-page_caching` RubyGems	before 1.2.1	1.2.1
`ruby-actionpack-page-caching` Debian:12	before 1.2.2-1	1.2.2-1
`ruby-actionpack-page-caching` Debian:9	before 1.0.2-4+deb9u1, plus listed versions 1.0.2-4	1.0.2-4+deb9u1
`actionpack-page_caching` RubyGems	before 1.2.1, plus listed versions 1.0.01.0.11.0.21.1.01.1.11.2.0	1.2.1
`ruby-actionpack-page-caching` Ubuntu:16.04:LTS	All versions, plus listed versions 1.0.2-31.0.2-4	None known
`ruby-actionpack-page-caching` Ubuntu:18.04:LTS	All versions, plus listed versions 1.0.2-4	None known
`ruby-actionpack-page-caching` Ubuntu:20.04:LTS	All versions, plus listed versions 1.1.0-1	None known

History

History
Recorded	Changed	Sources
Nov 3, 2026	aliases	EUVD
Nov 2, 2026	first indexed	CVE List, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2020-8159 is a critical vulnerability (CVSS 9.8) in Debian Linux, published May 12, 2020. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 5.38%, the 92nd percentile. Fixed in actionpack-page_caching 1.2.1.