CVE-2026-33170
Rails Active Support has a possible XSS vulnerability in SafeBuffer#%
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.
INFO
Published Date :
March 24, 2026, 12:16 a.m.
Last Modified :
March 24, 2026, 6 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | MEDIUM | [email protected] | ||||
| CVSS 4.0 | MEDIUM | [email protected] |
Solution
- Update Active Support to version 8.1.2.1 or later.
- Update Active Support to version 8.0.4.1 or later.
- Update Active Support to version 7.2.3.1 or later.
Public PoC/Exploit Available at Github
CVE-2026-33170 has a 1 public
PoC/Exploit available at Github.
Go to the Public Exploits tab to see the list.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-33170.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-33170 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-33170
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
None
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-33170 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-33170 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
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Initial Analysis by [email protected]
Mar. 24, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N Added CPE Configuration OR *cpe:2.3:a:rubyonrails:rails:*:*:*:*:*:*:*:* versions up to (excluding) 7.2.3.1 *cpe:2.3:a:rubyonrails:rails:*:*:*:*:*:*:*:* versions from (including) 8.0.0 up to (excluding) 8.0.4.1 *cpe:2.3:a:rubyonrails:rails:*:*:*:*:*:*:*:* versions from (including) 8.1.0 up to (excluding) 8.1.2.1 Added Reference Type GitHub, Inc.: https://github.com/rails/rails/commit/50d732af3b7c8aaf63cbcca0becbc00279b215b7 Types: Patch Added Reference Type GitHub, Inc.: https://github.com/rails/rails/commit/6e8a81108001d58043de9e54a06fca58962fc2db Types: Patch Added Reference Type GitHub, Inc.: https://github.com/rails/rails/commit/c1ad0e8e1972032f3395853a5e99cea035035beb Types: Patch Added Reference Type GitHub, Inc.: https://github.com/rails/rails/releases/tag/v7.2.3.1 Types: Release Notes Added Reference Type GitHub, Inc.: https://github.com/rails/rails/releases/tag/v8.0.4.1 Types: Release Notes Added Reference Type GitHub, Inc.: https://github.com/rails/rails/releases/tag/v8.1.2.1 Types: Release Notes Added Reference Type GitHub, Inc.: https://github.com/rails/rails/security/advisories/GHSA-89vf-4333-qx8v Types: Vendor Advisory -
New CVE Received by [email protected]
Mar. 24, 2026
Action Type Old Value New Value Added 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. Added CVSS V4.0 AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X Added CWE CWE-79 Added Reference https://github.com/rails/rails/commit/50d732af3b7c8aaf63cbcca0becbc00279b215b7 Added Reference https://github.com/rails/rails/commit/6e8a81108001d58043de9e54a06fca58962fc2db Added Reference https://github.com/rails/rails/commit/c1ad0e8e1972032f3395853a5e99cea035035beb Added Reference https://github.com/rails/rails/releases/tag/v7.2.3.1 Added Reference https://github.com/rails/rails/releases/tag/v8.0.4.1 Added Reference https://github.com/rails/rails/releases/tag/v8.1.2.1 Added Reference https://github.com/rails/rails/security/advisories/GHSA-89vf-4333-qx8v