CVE-2020-8159Network attack vector

Arbitrary file write via cache path traversal

Published May 12, 2020 · Updated Aug 4, 2024

Path traversal in Ruby on Rails Action Pack Page Caching before 1.2.1 allows remote attackers to write server files via crafted URLs. The cache_path method joined a request-derived cache filename to the cache directory without normalizing the result or verifying that it remained beneath that directory. A Rails action must use caches_page and caching must be enabled; code execution requires an attacker-controlled response body to be stored as unescaped ERB in a view directory.

CVSS severity9.8
Critical
EPSS probability5.25%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Path traversal in Ruby on Rails Action Pack Page Caching before 1.2.1 allows remote attackers to write server files via crafted URLs. The cache_path method joined a request-derived cache filename to the cache directory without normalizing the result or verifying that it remained beneath that directory. A Rails action must use caches_page and caching must be enabled; code execution requires an attacker-controlled response body to be stored as unescaped ERB in a view directory.

The record

CVE
CVE-2020-8159
Published
May 12, 2020
Updated
Aug 4, 2024
Vendor
Ruby on Rails
Product
Action Pack Page Caching
Classifications
CWE-22, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 12, 2020CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

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  1. Affected versionversion=v1.2.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Ruby on Rails · Action Pack Page Cachingversion=v1.2.1

Published CVSS scores

9.8GitHub Advisory DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-22Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
T1190Exploit Public-Facing Application

Public exploit references

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Technologies

Your stack

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Your stack

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