CVE-2026-55696

PrivateBin: Stored Cross-Side-Scripting (XSS) vulnerability in attachment download link via dangerous MIME types with required user-interaction

MEDIUM

4.3

CVSS Score

Published: August 28, 2026 at 08:20 PM UTC

Updated: September 9, 2026 at 09:27 PM UTC

1 product affected across 1 vendorPrivateBin

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Severity

MEDIUM4.3

Exploit prediction

EPSS 0.4%

SSVC

No known exploit

Description

PrivateBin is an online pastebin where the server has zero knowledge of pasted data. Prior to 2.0.5, AttachmentViewer.setAttachment in js/privatebin.js uses getAttachmentMimeType to accept attacker-controlled MIME types and uses getBlobUrl to create a same-origin blob before setting attachmentLink's href for the Download attachment link. The SVG-only sanitization branch updates only the preview blob, so text/html, image/svg, application/xhtml+xml, and text/xml attachments can remain active in the download blob. On an instance with fileupload = true and a weakened, stripped, or absent Content Security Policy, an anonymous attacker can create such an attachment, and a victim who opens the link in a new tab causes inline JavaScript to execute in the PrivateBin origin. The script can read origin-scoped local storage and issue same-origin requests, including requests to applications co-hosted on the same domain. This issue is fixed in version 2.0.5.