CVSS 3.1
4.7 mediumCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:L/A:NCVE-2026-128069 rails-html-sanitizer: Possible XSS via shared scrubber state in concurrent calls
Medium (4.7) in rails rails-html-sanitizer. Fixed in rails-html-sanitizer 1.7.2.
On this page
rails-html-sanitizer is responsible for sanitizing HTML fragments in Rails applications. Before 1.7.2, the HTML4 and HTML5 variants of Rails::HTML::SafeListSanitizer reuse one Rails::HTML::PermitScrubber across calls and mutate its tags and attributes without synchronization. In a multithreaded process, concurrent sanitize calls using different tags: or attributes: options can interleave and cause one call to use the other call's allowlist. If a permissive call admits a script element or event-handler attribute, output expected to be sanitized under a stricter policy can retain it and cause cross-site scripting when rendered. Applications that are single-threaded, use one identical allowlist everywhere, or provide a separate scrubber: are not affected. This issue is fixed in version 1.7.2.
Severity
- CWEs
- CWE-79 Improper Neutralization of Input During Web Page Generation (Cross-site Scripting)
CWE-362 Concurrent Execution using Shared Resource with Improper Synchronization (Race Condition) - OWASP Top 10
- A05:2025 Injection, A06:2025 Insecure Design
- Published
- Assigned by
- GitHub_M (CNA)
- NVD analysis
- Awaiting analysis
- Record from
- the NVD, synced
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Affected
Versions
From the CNA's record in the CVE List.
| Product | Affected |
|---|---|
| rails-html-sanitizer | < 1.7.2 |
Fix and patched versions
rails-html-sanitizer(RubyGems): fixed in 1.7.2
Packages (OSV)
| Advisory | Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|---|
| GHSA-h7wh-q2qr-458c | RubyGems | rails-html-sanitizer | <1.7.2 | 1.7.2 |
Attack patterns (CAPEC)
- CAPEC-26 Leveraging Race Conditions Likelihood: High · Severity: High
- CAPEC-29 Leveraging Time-of-Check and Time-of-Use (TOCTOU) Race Conditions Likelihood: High · Severity: High
- CAPEC-63 Cross-Site Scripting (XSS) Likelihood: High · Severity: Very High
- CAPEC-85 AJAX Footprinting Likelihood: High · Severity: Low
- CAPEC-209 XSS Using MIME Type Mismatch Severity: Medium
- CAPEC-588 DOM-Based XSS Likelihood: High · Severity: Very High
- CAPEC-591 Reflected XSS Likelihood: High · Severity: Very High
- CAPEC-592 Stored XSS Likelihood: High · Severity: Very High
The attack patterns MITRE's CAPEC relates to this record's weaknesses, as MITRE names them. Credits.