CVE-2026-46426: Budibase Unrestricted File Upload Vulnerability Leading to Persistent XSS
Summary
CVE-2026-46426: Budibase: Unrestricted Upload of File with Dangerous Type. Affects budibase versions < 3.38.2. Fixed in 3.38.2. How to fix ↓
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Background
Budibase is an open-source low-code platform that enables users to build applications quickly and efficiently. It allows for the creation of custom applications with a focus on ease of use and rapid deployment. However, a critical vulnerability has been identified in the file upload functionality, which could allow authenticated users to upload malicious files, leading to severe security risks.
Vulnerability Detail
The vulnerability arises from the file upload endpoint POST /api/attachments/process, which fails to enforce restrictions on dangerous file types for authenticated users. The checks for file extensions such as HTML, SVG, JS, and PHP are conditionally applied, allowing any authenticated builder to upload executable web content. This results in persistent stored XSS, where malicious scripts can be executed in the browsers of all application end users, potentially leading to session cookie theft and full account takeover.
How To Fix
Latest published version: 0.0.31 as of 23 Oct 2026
npm install budibase@0.0.31Upgrading to it may include breaking changes; the version below is the minimum fixed release for this vulnerability.
If you need the minimum change
3.38.2
This is the first release that contains the fix.
npm install budibase@3.38.2Tip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
As a temporary workaround, restrict file uploads to non-executable file types until the package is updated. This can be done by modifying the file upload logic to only allow image formats such as JPEG, PNG, or GIF.
Conclusion
The CVE-2026-46426 vulnerability in Budibase poses a significant risk due to unrestricted file uploads, allowing for persistent XSS attacks. It is crucial for users to update their Budibase installations to the patched version 3.38.2 or later to safeguard against potential exploits.
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FAQ
CVE-2026-46426 is a vulnerability in Budibase that allows authenticated users to upload files with dangerous types, leading to persistent XSS attacks.
You can use Vulert's playground at Vulert Scanner to check if your application is affected by this vulnerability without any signup.
The vulnerability can lead to session cookie theft, allowing attackers to take over user accounts and potentially compromise the entire application.
Yes, a patch is available in Budibase version 3.38.2 and later. It is recommended to update to this version to mitigate the risk.
The CVSS score of this vulnerability is 7.6, indicating a high severity level.
References
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