CVE-2024-32970 is a high-severity (CVSS 7.1) Cross-site Scripting (XSS) vulnerability in phlex. A fix is available for phlex — see the affected versions and patch details below.
Cross-site Scripting (XSS) possible with maliciously formed HTML attribute names and values in Phlex
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2024-32970.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
phlex💎phlexReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects RubyGems packages — download data is not available via public APIs for these ecosystems.
Description
Phlex is a framework for building object-oriented views in Ruby. In affected versions there is a potential cross-site scripting (XSS) vulnerability that can be exploited via maliciously crafted user data. Since the last two vulnerabilities https://github.com/phlex-ruby/phlex/security/advisories/GHSA-242p-4v39-2v8g and https://github.com/phlex-ruby/phlex/security/advisories/GHSA-g7xq-xv8c-h98c, we have invested in extensive browser tests. It was these new tests that helped us uncover these issues. As of now the project exercises every possible attack vector the developers can think of — including enumerating every ASCII character, and we run these tests in Chrome, Firefox and Safari. Additionally, we test against a list of 6613 known XSS payloads (see: payloadbox/xss-payload-list). The reason these issues were not detected before is the escapes were working as designed. However, their design didn't take into account just how recklessly permissive browsers are when it comes to executing unsafe JavaScript via HTML attributes. If you render an <a> tag with an href attribute set to a user-provided link, that link could potentially execute JavaScript when clicked by another user. If you splat user-provided attributes when rendering any HTML or SVG tag, malicious event attributes could be included in the output, executing JavaScript when the events are triggered by another user. Patches are available on RubyGems for all minor versions released in the last year. Users are advised to upgrade. Users unable to upgrade should configure a Content Security Policy that does not allow unsafe-inline which would effectively prevent this vulnerability from being exploited. Users who upgrade are also advised to configure a Content Security Policy header that does not allow unsafe-inline.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 💎RubyGems | phlex | all versions | 1.9.3bundle update phlex --conservative |
| 💎RubyGems | phlex | ≥ 1.10.0&&< 1.10.2 | 1.10.2bundle update phlex --conservative |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for phlex, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update phlex to 1.9.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2024-32970 is resolved across your whole dependency graph.
Workarounds
Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.
Frequently Asked Questions
Is CVE-2024-32970 in your dependencies?
Find it across RubyGems, including transitive dependencies.