CVE-2026-3254 | GitLab Community Edition/Enterprise Edition up to 18.11.0 Mermaid Sandbox ui layer (EUVD-2026-24961)

VDB-359027 · CVE-2026-3254 · EUVD-2026-24961 GITLAB COMMUNITY EDITION/ENTERPRISE EDITION UP TO 18.11.0 MERMAID SANDBOX UI LAYER HISTORYDIFFRELATEJSONXMLCTI CVSS Meta Temp Score Current Exploit Price (≈) CTI Interest Score 3.4 $0-$5k 1.91+ Summaryinfo A vulnerability marked as problematic has been reported in GitLab Community Edition and Enterprise Edition up to 18.11.0. This impacts an unknown function of the component Mermaid Sandbox. The manipulation leads to ui layer. This vulnerability is uniquely identified as CVE-2026-3254. The attack is possible to be carried out remotely. No exploit exists. It is suggested to upgrade the affected component. Detailsinfo A vulnerability was found in GitLab Community Edition and Enterprise Edition up to 18.11.0. It has been rated as problematic. This issue affects an unknown code of the component Mermaid Sandbox. The manipulation with an unknown input leads to a ui layer vulnerability. Using CWE to declare the problem leads to CWE-1021. The web application does not restrict or incorrectly restricts frame objects or UI layers that belong to another application or domain, which can lead to user confusion about which interface the user is interacting with. Impacted is integrity. The summary by CVE is: 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. The weakness was disclosed by joaxcar. It is possible to read the advisory at hackerone.com. The identification of this vulnerability is CVE-2026-3254 since 02/26/2026. The exploitation is known to be easy. The attack may be initiated remotely. It demands that the victim is doing some kind of user interaction. The technical details are unknown and an exploit is not publicly available. Upgrading to version 18.11.1 eliminates this vulnerability. The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-24961). Productinfo Type Bug Tracking Software Vendor GitLab Name Community Edition Enterprise Edition Version 18.0 18.1 18.2 18.3 18.4 18.5 18.6 18.7 18.8 18.9 18.10 18.11.0 License open-source Website Vendor: https://gitlab.com/ CPE 2.3info 🔒 🔒 🔒 CPE 2.2info 🔒 🔒 🔒 CVSSv4info VulDB Vector: 🔒 VulDB Reliability: 🔍 CVSSv3info VulDB Meta Base Score: 3.5 VulDB Meta Temp Score: 3.4 VulDB Base Score: 3.5 VulDB Temp Score: 3.4 VulDB Vector: 🔒 VulDB Reliability: 🔍 CNA Base Score: 3.5 CNA Vector (GitLab): 🔒 CVSSv2info Vector Complexity Authentication Confidentiality Integrity Availability Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock VulDB Base Score: 🔒 VulDB Temp Score: 🔒 VulDB Reliability: 🔍 Exploitinginfo Class: Ui layer CWE: CWE-1021 CAPEC: 🔒 ATT&CK: 🔒 Physical: No Local: No Remote: Yes Availability: 🔒 Status: Not defined Price Prediction: 🔍 Current Price Estimation: 🔒 0-Day Unlock Unlock Unlock Unlock Today Unlock Unlock Unlock Unlock Threat Intelligenceinfo Interest: 🔍 Active Actors: 🔍 Active APT Groups: 🔍 Countermeasuresinfo Recommended: Upgrade Status: 🔍 0-Day Time: 🔒 Upgrade: Community Edition/Enterprise Edition 18.11.1 Timelineinfo 02/26/2026 CVE reserved 04/22/2026 +54 days Advisory disclosed 04/22/2026 +0 days VulDB entry created 04/22/2026 +0 days VulDB entry last update Sourcesinfo Vendor: gitlab.com Advisory: hackerone.com Researcher: joaxcar Status: Confirmed CVE: CVE-2026-3254 (🔒) GCVE (CVE): GCVE-0-2026-3254 GCVE (VulDB): GCVE-100-359027 EUVD: 🔒 Entryinfo Created: 04/22/2026 19:03 Updated: 04/22/2026 21:25 Changes: 04/22/2026 19:03 (66), 04/22/2026 21:25 (1) Complete: 🔍 Cache ID: 99:015:101 Discussion No comments yet. Languages: en. Please log in to comment. ◂ PreviousOverviewNext ▸