CVE-2020-8264
MediumCross-site scripting in actionpack
Published Apr 7, 2021 · Updated Sep 9, 2026 · Also known as DEBIAN-CVE-2020-8264, GHSA-35mm-cc6r-8fjp
Key Facts
Patch immediately- CVE-2020-8264 is a medium-severity vulnerability (CVSS 6.1 v3.1) affecting Rails (Rubyonrails), actionpack (rubygems), ruby2.7-rubygem-actioncable-6.0 (suse) and 22 more products.
- It is not listed in any known-exploited vulnerabilities catalog. No public exploit code is known.
- EPSS estimates a 67% probability of exploitation in the next 30 days.
- Fixed versions are available, including actionpack 6.0.3.4, Rails 2:6.0.3.4+dfsg-1, Rails 6.0.3.4.
- Brandefense priority: patch immediately, because it is very likely to be exploited soon.
CVSS v3.1
6.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
EPSS (30-day exploit likelihood)
67%
Higher than 99.2% of all scored CVEs
Exploited in the wild
No known
Not in a known-exploited catalog
Public exploit code
None known
Get the full CVE-2020-8264 brief as a PDF
Every affected product and fixed release, exploitation status and a first 24 hours response checklist, emailed within minutes.
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.
Affected Products
53 affected entries in total| Product | Affected versions | Fixed in |
|---|---|---|
| RailsRubyonrails | See advisory | 6.0.3.4 |
| actionpackrubygems | >= 6.0.0 | 6.0.3.4 |
| ruby2.7-rubygem-actioncable-6.0suse | See advisory | 6.0.4-1.2 |
| ruby2.7-rubygem-actionmailbox-6.0suse | See advisory | 6.0.4-1.2 |
| ruby2.7-rubygem-actionmailer-6.0suse | See advisory | 6.0.4-1.2 |
Patched Releases
actionpack
6.0.3.4
Rails
2:6.0.3.4+dfsg-1, 6.0.3.4
ruby2.7-rubygem-actioncable-6.0
6.0.4-1.2
ruby2.7-rubygem-actionmailbox-6.0
6.0.4-1.2
ruby2.7-rubygem-actionmailer-6.0
6.0.4-1.2
ruby2.7-rubygem-actionpack-6.0
6.0.4-1.2
ruby2.7-rubygem-actiontext-6.0
6.0.4-1.2
ruby2.7-rubygem-actionview-6.0
6.0.4-1.2
ruby2.7-rubygem-activejob-6.0
6.0.4-1.2
ruby2.7-rubygem-activemodel-6.0
6.0.4-1.2
ruby2.7-rubygem-activerecord-6.0
6.0.4-1.2
ruby2.7-rubygem-activestorage-6.0
6.0.4-1.2
ruby2.7-rubygem-activesupport-6.0
6.0.4-1.2
ruby2.7-rubygem-rails-6.0
6.0.4-1.2
ruby2.7-rubygem-railties-6.0
6.0.4-1.2
ruby3.0-rubygem-actioncable-6.0
6.0.4-1.2
ruby3.0-rubygem-actionmailbox-6.0
6.0.4-1.2
ruby3.0-rubygem-actionmailer-6.0
6.0.4-1.2
ruby3.0-rubygem-actionpack-6.0
6.0.4-1.2
ruby3.0-rubygem-actiontext-6.0
6.0.4-1.2
ruby3.0-rubygem-actionview-6.0
6.0.4-1.2
ruby3.0-rubygem-activejob-6.0
6.0.4-1.2
ruby3.0-rubygem-activemodel-6.0
6.0.4-1.2
ruby3.0-rubygem-activerecord-6.0
6.0.4-1.2
ruby3.0-rubygem-activestorage-6.0
6.0.4-1.2
Timeline
Publicly disclosed
Apr 7, 2021
Last updated
Sep 9, 2026
Weakness Type
- CWE-79 Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
References
- advisoryGHSA advisory
- advisoryhttps://nvd.nist.gov/vuln/detail/CVE-2020-8264
- advisoryhttps://security-tracker.debian.org/tracker/CVE-2020-8264
- articlehttps://github.com/rubysec/ruby-advisory-db/blob/master/gems/actionpack/CVE-2020-8264.yml
- articlehttps://groups.google.com/g/rubyonrails-security/c/yQzUVfv42jk
FAQ
Common Questions.
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.
Affected: Rails (Rubyonrails); actionpack (rubygems) versions >= 6.0.0; ruby2.7-rubygem-actioncable-6.0 (suse), among others. The full list is in the CVE brief.
It is not listed in any known-exploited vulnerabilities catalog.
No, it is not currently listed in the CISA Known Exploited Vulnerabilities catalog.
No public exploit code is known.
Fixed versions are available, including actionpack 6.0.3.4, Rails 2:6.0.3.4+dfsg-1, Rails 6.0.3.4.
Brandefense priority: patch immediately, because it is very likely to be exploited soon.
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