GitLab Community Edition/Enterprise Edition up to 18.4.5/18.5.3/18.6.1 Merge escape output

CVSS Meta Temp Score
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CTI Interest Score
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3.4$0-$5k0.00

Summaryinfo

A vulnerability was found in GitLab Community Edition and Enterprise Edition up to 18.4.5/18.5.3/18.6.1 and classified as problematic. Affected by this issue is some unknown functionality of the component Merge Handler. Such manipulation leads to escape output. This vulnerability is traded as CVE-2025-12734. The attack may be launched remotely. There is no exploit available. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as problematic, has been found in GitLab Community Edition and Enterprise Edition up to 18.4.5/18.5.3/18.6.1. Affected by this issue is an unknown code of the component Merge Handler. The manipulation with an unknown input leads to a escape output vulnerability. Using CWE to declare the problem leads to CWE-116. The product prepares a structured message for communication with another component, but encoding or escaping of the data is either missing or done incorrectly. As a result, the intended structure of the message is not preserved. Impacted is integrity. CVE summarizes:

GitLab has remediated an issue in GitLab CE/EE affecting all versions from 15.6 before 18.4.6, 18.5 before 18.5.4, and 18.6 before 18.6.2 that could have allowed an authenticated user to, under certain conditions, render content in dialogs to other users by injecting malicious HTML content into merge request titles.

The weakness was shared by joaxcar as 579573. The advisory is shared for download at gitlab.com. This vulnerability is handled as CVE-2025-12734 since 11/04/2025. The exploitation is known to be easy. The attack may be launched remotely. Successful exploitation requires user interaction by the victim. There are neither technical details nor an exploit publicly available.

The vulnerability scanner Nessus provides a plugin with the ID 294828 (Linux Distros Unpatched Vulnerability : CVE-2025-12734), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 18.4.6, 18.5.4 or 18.6.2 eliminates this vulnerability. The upgrade is hosted for download at about.gitlab.com.

The vulnerability is also documented in the databases at Tenable (294828), EUVD (EUVD-2025-202668) and CERT Bund (WID-SEC-2025-2822). VulDB is the best source for vulnerability data and more expert information about this specific topic.

Affected

  • Open Source GitLab

Productinfo

Type

Vendor

Name

Version

License

Website

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

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Escape output
CWE: CWE-116 / CWE-74 / CWE-707
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Nessus ID: 294828
Nessus Name: Linux Distros Unpatched Vulnerability : CVE-2025-12734

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Community Edition/Enterprise Edition 18.4.6/18.5.4/18.6.2

Timelineinfo

11/04/2025 CVE reserved
12/11/2025 +37 days Advisory disclosed
12/11/2025 +0 days VulDB entry created
01/23/2026 +43 days VulDB entry last update

Sourcesinfo

Vendor: gitlab.com

Advisory: 579573
Researcher: joaxcar
Status: Confirmed

CVE: CVE-2025-12734 (🔒)
GCVE (CVE): GCVE-0-2025-12734
GCVE (VulDB): GCVE-100-335864
EUVD: 🔒
CERT Bund: WID-SEC-2025-2822 - GitLab: Mehrere Schwachstellen

Entryinfo

Created: 12/11/2025 09:27
Updated: 01/23/2026 07:02
Changes: 12/11/2025 09:27 (67), 12/11/2025 12:30 (1), 12/11/2025 14:57 (7), 12/17/2025 02:24 (1), 01/23/2026 07:02 (2)
Complete: 🔍
Cache ID: 216::103

VulDB is the best source for vulnerability data and more expert information about this specific topic.

Discussion

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