CVE-2025-3950Network attack vector

Connection-data disclosure via unproxied Mermaid images

Published Jan 9, 2026 · Updated Jan 9, 2026

Information disclosure in affected GitLab CE/EE releases allows remote authenticated users to expose viewer connection data through Mermaid images. The Mermaid renderer accepts crafted external image references that bypass the configured asset proxy, causing a viewer's browser to contact an attacker-controlled server directly. Asset proxying must be enabled and a user must view the rendered diagram; the reported impact is limited to sensitive connection information.

CVSS severity3.5
Low
EPSS probability0.27%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Information disclosure in affected GitLab CE/EE releases allows remote authenticated users to expose viewer connection data through Mermaid images. The Mermaid renderer accepts crafted external image references that bypass the configured asset proxy, causing a viewer's browser to contact an attacker-controlled server directly. Asset proxying must be enabled and a user must view the rendered diagram; the reported impact is limited to sensitive connection information.

The record

CVE
CVE-2025-3950
Published
Jan 9, 2026
Updated
Jan 9, 2026
Vendor
GitLab
Product
GitLab
Classifications
CWE-359
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jan 9, 2026CVE publishedPublication date reported by the CVE source.
  2. Jan 9, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=10.3 <18.5.5
  2. Affected versionversion=18.6 <18.6.3
  3. Affected versionversion=18.7 <18.7.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

GitLab · GitLabversion=10.3 <18.5.5; version=18.6 <18.6.3; version=18.7 <18.7.1

Published CVSS scores

3.5GitLab Inc.CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:N/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-359Exposure of Private Personal Information to an Unauthorized Actor

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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