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CVE-2026-33170

Rails Active Support has a possible XSS vulnerability in SafeBuffer#%

Published: Mar 23, 2026Updated: Mar 24, 2026 Sources: CVE List NVD BDUCWE-79
6.1MEDIUM
NVD MITRE
EPSS Score
0.3%
Top 75.6%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
Patch Available

Description

Active Support is a toolkit of support libraries and Ruby core extensions extracted from the Rails framework. Prior to versions 8.1.2.1, 8.0.4.1, and 7.2.3.1, `SafeBuffer#%` does not propagate the `@html_unsafe` flag to the newly created buffer. If a `SafeBuffer` is mutated in place (e.g. via `gsub!`) and then formatted with `%` using untrusted arguments, the result incorrectly reports `html_safe? == true`, bypassing ERB auto-escaping and possibly leading to XSS. Versions 8.1.2.1, 8.0.4.1, and 7.2.3.1 contain a patch.

No summary for this CVE yet.

CVSS Vector Breakdown

AV:NAC:LPR:NUI:RS:CC:LI:LA:N
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:NPrivileges Required
None
UI:RUser Interaction
Required
Scope
S:CScope
Changed
Impact
C:LConfidentiality
Low
I:LIntegrity
Low
A:NAvailability
None
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Weaknesses

CWE-79

Affected Products

railsrubyonrailsOSS Libraries
activesupportrails
Library
OSS Libraries / web-framework
РЕД ОСООО «Ред Софт»
On-premOS
Operating Systems / linux-distro
Red Hat SatelliteRed Hat Inc.
On-prem
Operating Systems / linux-distro
Ruby on RailsRails Core Team
Library
OSS Libraries / web-framework
rubyonrailsoss-projectUSOSS Librariesaka rails, ruby on rails, rubyonrails.org
railsoss-projectOSS Librariesaka rails-html-sanitizer, activestorage
ооо «ред софт»commercialRUOperating Systemsaka red soft
red hat inc.commercialUSOperating Systemsaka red hat
rails core teamoss-projectOSS Librariesaka rubyonrails, rails, actionview, rack? no

Exploitability

Official Patch Available

Attack Graph

Products CVE Techniques Tactics

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MITRE ATT&CK

2 techniques
Execution
Initial Access
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References

https://github.com/rails/rails/commit/50d732af3b7c8aaf63cbcca0becbc00279b215b7
github.com
https://github.com/rails/rails/commit/6e8a81108001d58043de9e54a06fca58962fc2db
github.com
https://github.com/rails/rails/commit/c1ad0e8e1972032f3395853a5e99cea035035beb
github.com
and 14 more references View all →

Timeline

Published
Mar 23, 2026
Last Updated
Mar 24, 2026

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