CVE-2026-3254

LOW

Improper Restriction of Rendered UI Layers or Frames in GitLab

Title source: cna

Description

GitLab has remediated an issue in GitLab CE/EE affecting all versions from 18.11 before 18.11.1 that under certain conditions could have allowed an authenticated user to load unauthorized content into another user's browser due to improper input validation in the Mermaid sandbox.

References (2)

Core 2

Core References

Exploit technical-description exploit permissions-required

HackerOne Bug Bounty Report #3572752

https://hackerone.com/reports/3572752

https://gitlab.com/gitlab-org/gitlab/-/work_items/591587

Scores

CVSS v3 3.5

EPSS 0.0015

EPSS Percentile 4.7%

Attack Vector NETWORK

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:L/A:N

CISA SSVC

Vulnrichment

Exploitation none

Automatable no

Technical Impact partial

Details

CWE

CWE-1021

Status published

Products (2)

gitlab/gitlab 18.11.0 (2 CPE variants)

GitLab/GitLab 18.11 - 18.11.1

Published Apr 22, 2026

Tracked Since Apr 22, 2026