PatchSiren cyber security CVE debrief
CVE-2026-9519 stonith404 CVE debrief
A reflected cross-site scripting (XSS) vulnerability exists in Pingvin Share versions up to and including 1.13.0. The flaw resides in the `getServerSideProps` function within `frontend/src/pages/auth/signIn.tsx`, where unsanitized user input passed via the `redirect` parameter is reflected into the page response. An attacker can craft a malicious URL containing JavaScript in the redirect parameter, which executes in the victim's browser when they visit the sign-in page. The vulnerability requires user interaction (clicking a malicious link) and has been publicly disclosed with exploit details available. The vendor was reportedly contacted prior to disclosure but did not respond.
- Vendor
- stonith404
- Product
- pingvin-share
- CVSS
- LOW 2.1
- CISA KEV
- Not listed in stored evidence
- Original CVE published
- 2026-05-26
- Original CVE updated
- 2026-05-26
- Advisory published
- 2026-05-26
- Advisory updated
- 2026-05-26
Who should care
Organizations self-hosting Pingvin Share instances for internal or external file sharing; security teams monitoring open-source application vulnerabilities; developers implementing authentication flows with redirect parameters
Technical summary
The vulnerability is a reflected XSS in the sign-in auto-redirect functionality of Pingvin Share, an open-source file sharing platform. The `getServerSideProps` Next.js function in `frontend/src/pages/auth/signIn.tsx` reflects the `redirect` query parameter into the page without proper output encoding or validation. This allows injection of arbitrary JavaScript that executes in the context of the victim's session. The attack is delivered via a crafted URL and requires the victim to visit the malicious link. The CVSS 4.0 score of 2.1 (LOW) reflects the user interaction requirement and limited integrity impact, though session hijacking or credential theft remains possible depending on application context.
Defensive priority
P3
Recommended defensive actions
- Review and sanitize all user-supplied redirect parameters in authentication flows using allowlist-based validation
- Implement Content Security Policy (CSP) headers to mitigate impact of XSS vulnerabilities
- Upgrade to Pingvin Share version 1.13.1 or later when available, or apply vendor-provided patches
- Monitor authentication endpoints for anomalous redirect parameter patterns in web application logs
- Consider implementing additional redirect validation that ensures destinations match expected application domains
Evidence notes
Vulnerability confirmed via Vuldb entry and associated Gist reference. CVSS 4.0 vector indicates network attack vector, low attack complexity, no privileges required, and user interaction required. CWE-79 (XSS) and CWE-94 (Code Injection) classifications applied by CNA.
Official resources
Public disclosure occurred on 2026-05-26 with exploit details published. No vendor patch or response has been documented.