Vulnerability · Published Jun 24, 2026 · Assigned by GitHub_M

CVE-2026-52816Gogs: Unauthenticated Jupyter Notebook (ipynb) Sanitizer allows arbitrary data: URIs leading to XSS

Medium 5.4

In plain English

A medium-severity security flaw in gogs from gogs. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.7% (higher than 52% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 4.0)5.4Medium

Exploit odds (30 days)0.7%top 47.6% of all CVEs

Exploited in the wildNo reportsCISA SSVC: poc

Attack toolingNoneno public tooling known

Official description

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.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
Go	gogs.io/gogs	0.14.3	GHSA-3w28-36p9-w929
Go	gogs.io/gogs	no fix listed	GO-2026-5103

Affected products (as reported)

Vendor	Product	Versions
gogs	gogs	< 0.14.3

Weakness: CWE-80 · 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

References

https://github.com/gogs/gogs/security/advisories/GHSA-3w28-36p9-w929 x_refsource_CONFIRM
https://github.com/gogs/gogs/pull/8326 x_refsource_MISC
https://github.com/gogs/gogs/commit/dd1bd9837aa196b3ed3a8ee21e5727b5d7a986a3 x_refsource_MISC
https://github.com/gogs/gogs/releases/tag/v0.14.3 x_refsource_MISC