CVE-2026-42150: wlc Package Cross-Site Scripting Vulnerability Due to HTML Output
Summary
CVE-2026-42150: wlc: print_html outputs API data without HTML escaping. Affects wlc versions < 2.0.0. Fixed in 2.0.0. How to fix ↓
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Background
The 'wlc' package is a web-based localization tool that facilitates the translation of software projects. It allows developers to manage and collaborate on translations efficiently. However, a critical vulnerability has been identified in its HTML output functionality, which can lead to security risks if not addressed.
Vulnerability Detail
The vulnerability arises from the 'print_html' function in the wlc package, which outputs API response data directly into HTML without proper escaping. This oversight can lead to cross-site scripting (XSS) attacks when the output is rendered in a web browser. Attackers can exploit this flaw to inject malicious scripts, potentially compromising user data and application integrity.
How To Fix
Latest published version: 3.1.0 as of 23 Oct 2026
pip install --upgrade "wlc==3.1.0"Upgrading to it may include breaking changes; the version below is the minimum fixed release for this vulnerability.
If you need the minimum change
2.0.0
This is the first release that contains the fix.
pip install --upgrade "wlc==2.0.0"Tip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
As a temporary workaround, avoid using the HTML output feature of the wlc package, as the vulnerable code path is opt-in. This means that if you do not explicitly request HTML output, your application will not be affected by this vulnerability.
Conclusion
The wlc package has a vulnerability that can lead to cross-site scripting attacks due to improper handling of HTML output. It is crucial to update to the latest version to mitigate this risk. Users should also consider using Vulert to monitor for vulnerabilities in their applications.
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FAQ
The vulnerability allows for cross-site scripting (XSS) due to unescaped API response data being embedded in HTML.
You can use the Vulert playground at Vulert Scanner to check if your application is affected by this vulnerability without needing to sign up.
The CVSS score for this vulnerability is 5.1, indicating a moderate severity level.
Yes, the vulnerability has been patched in version 2.0.0 of the wlc package. It is recommended to update to this version.
If an immediate update is not possible, refrain from using the HTML output feature of the wlc package as a temporary workaround.
References
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