CVE-2026-33167

Rails has a possible XSS vulnerability in its Action Pack debug exceptions

MEDIUM
6.1
CVSS Score
Published: March 23, 2026 at 10:58 PM UTC
Updated: August 12, 2026 at 04:58 PM UTC
2 products affected across 2 vendorsRailsRails

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Severity
MEDIUM6.1
Exploit prediction
EPSS 0.3%
SSVC
No known exploit

Description

Action Pack is a Rubygem for building web applications on the Rails framework. In versions on the 8.1 branch prior to 8.1.2.1, the debug exceptions page does not properly escape exception messages. A carefully crafted exception message could inject arbitrary HTML and JavaScript into the page, leading to XSS. This affects applications with detailed exception pages enabled (`config.consider_all_requests_local = true`), which is the default in development. Version 8.1.2.1 contains a patch.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

8.1.0 ≤ v < 8.1.2.1
Affected range stops below 8.1.2.1, so it looks safe — our inference, not a vendor statement
v < 8.1.2.1
Affected range stops below 8.1.2.1, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

References (3)

x_refsource_CONFIRMVendor Advisory
Source: cverecord
https://github.com/rails/rails/security/advisories/GHSA-pgm4-439c-5jp6
x_refsource_MISCRelease Notes
Source: cverecord
https://github.com/rails/rails/releases/tag/v8.1.2.1

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
REQUIRED
Scope
CHANGED
Confidentiality
LOW
Integrity
LOW
Availability
NONE
Vector?

Quick Info

StatusANALYZED
CWE
CWE-79

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