CVE-2026-52816CWE-80

Gogs: Unauthenticated Jupyter Notebook (ipynb) Sanitizer allows arbitrary data: URIs leading to XSS

Medium · published June 24, 2026

CVSS v4.0
5.4
EPSS
1%
Percentile
51.7
In the wild
Unconfirmed
What it is

Gogs is an open source self-hosted Git service. Prior to 0.14.3, the Jupyter Notebook (ipynb) sanitizer endpoint at POST /-/api/sanitize_ipynb allows arbitrary data: URIs without proper restrictions, potentially leading to Cross-Site Scripting (XSS). The endpoint uses bluemonday.UGCPolicy() with p.AllowURLSchemes("data") which permits all data URI schemes including data:text/html, enabling attackers to inject malicious HTML/JavaScript. Additionally, the endpoint has no authentication middleware, allowing any registered user to exploit this vulnerability. This vulnerability is fixed in 0.14.3.

The record
Technical detail
CVSS v4.0
5.4 · MEDIUM
Vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N/E:P
EPSS
0.00677 · 51.7th percentile
Weakness
CWE-80 · Improper Neutralization of Script-Related HTML Tags in a Web Page (Basic XSS)
Published
2026-06-24T20:26Z
EPSS history
Timeline
  • 24 JUN 20:26Z
    Gogs: Unauthenticated Jupyter Notebook (ipynb) Sanitizer allows arbitrary data: URIs leading to XSS
    cvelistv5