CVE-2020-8264

Name: CVE-2020-8264
Creator: NVD / NIST
Published: 2021-01-06T21:15:14.363+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 6.1/10EPSS 70.72%

Last modified Jun 17, 2026

CVE-2020-8264 is a medium-severity vulnerability rated 6.1/10 on the CVSS scale. In actionpack gem >= 6.0.0, a possible XSS vulnerability exists when an application is running in development mode allowing an attacker to send or embed (in another page) a specially crafted URL which can allow the attacker to execute JavaScript in the context of the local application. This vulnerability is in the Actionable Exceptions middleware.. EPSS estimates a 70.72% chance of exploitation in the next 30 days.

Description

In actionpack gem >= 6.0.0, a possible XSS vulnerability exists when an application is running in development mode allowing an attacker to send or embed (in another page) a specially crafted URL which can allow the attacker to execute JavaScript in the context of the local application. This vulnerability is in the Actionable Exceptions middleware.

Metrics

CVSS 3.1

6.1/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

EPSS Probability

70.72%

99.3th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Rubyonrails	Rails	>= 6.0.0, < 6.0.3.4

References

https://groups.google.com/g/rubyonrails-security/c/yQzUVfv42jk/m/oJWw-xhNAQAJMailing List, Third Party Advisory
https://hackerone.com/reports/904059Exploit, Patch, Third Party Advisory
https://groups.google.com/g/rubyonrails-security/c/yQzUVfv42jk/m/oJWw-xhNAQAJMailing List, Third Party Advisory
https://hackerone.com/reports/904059Exploit, Patch, Third Party Advisory

Timeline

Published: Jan 6, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2020-8264?

How severe is CVE-2020-8264?

CVE-2020-8264 has a CVSS score of 6.1/10 (MEDIUM severity). The EPSS model estimates a 70.72% probability of exploitation in the next 30 days.

How do I fix CVE-2020-8264?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2020-8264?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST