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Fencer Vulns
medium 6.1

CVE-2020-8264 json

Cross-site scripting in actionpack

published 2021-01-06 5 y ago modified 2026-06-17 4 mo ago also GHSA-35mm-cc6r-8fjp , EUVD-2021-0742

cvss
6.1
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
67.0%
EPSS 67.0% chance of exploitation in 30 days, percentile 99.3%
public exploits
0
none known

Summary

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.

Patch / fix

  • rubygems actionpack 6.0.3.4
  • rubyonrails rails 6.0.3.4
  • rails Debian 14, Debian 13, Debian 12 2:6.0.3.4+dfsg-1

debian advisories DEBIAN-CVE-2020-8264

  • rubygem-actioncable-6.0 openSUSE Tumbleweed 6.0.4.4-1.1
  • rubygem-actionmailbox-6.0 openSUSE Tumbleweed 6.0.4.4-1.1
  • rubygem-actionmailer-6.0 openSUSE Tumbleweed 6.0.4.4-1.1
  • rubygem-actionpack-6.0 openSUSE Tumbleweed 6.0.4.4-1.1
  • rubygem-actiontext-6.0 openSUSE Tumbleweed 6.0.4.4-1.1
  • rubygem-actionview-6.0 openSUSE Tumbleweed 6.0.4.4-1.1
  • rubygem-activejob-6.0 openSUSE Tumbleweed 6.0.4.4-1.1
  • rubygem-activemodel-6.0 openSUSE Tumbleweed 6.0.4.4-1.1

opensuse advisories openSUSE-SU-2024:11818-1openSUSE-SU-2024:11819-1openSUSE-SU-2024:11820-1openSUSE-SU-2024:11821-1openSUSE-SU-2024:11822-1openSUSE-SU-2024:11823-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2020-8264 updated cvss 7.7

rubygem-actionpack: possible XSS vulnerability in Action Pack in development mode

  • Red Hat CloudForms Management Engine 5 cfme-gemset, cfme-amazon-smartstate Red Hat Satellite 6 tfm-rubygem-actionpack, tfm-ror52-rubygem-rails
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

66.99% chance of exploitation in the next 30 days, higher than 99.3% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • hackerone.com https://hackerone.com/reports/904059 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.1 6.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
NVD 2.0 4.3 AV:N/AC:M/Au:N/C:N/I:P/A:N
GitHub 3.1 6.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Affected packages

ecosystem package affected fixed in
rubygems actionpack
>=6.0.0, <6.0.3.4
6.0.3.4

Affected products

  • n/a https://github.com/rails/rails

Classification

Weakness
  • CWE-79 Improper Neutralization of Input During Web Page Generation
Technology feeds

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.