Yuzutech Kroki up to 0.31.1 Mermaid Companion mermaid/src/worker.js server-side request forgery

Summaryinfo

A vulnerability classified as critical was found in Yuzutech Kroki up to 0.31.1. The impacted element is an unknown function of the file mermaid/src/worker.js of the component Mermaid Companion. The manipulation results in server-side request forgery. This vulnerability is cataloged as CVE-2026-102356. The attack may be launched remotely. There is no exploit available. Upgrading the affected component is advised.

Detailsinfo

A vulnerability classified as critical has been found in Yuzutech Kroki up to 0.31.1. Affected is an unknown function of the file mermaid/src/worker.js of the component Mermaid Companion. The manipulation with an unknown input leads to a server-side request forgery vulnerability. CWE is classifying the issue as CWE-918. The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination. This is going to have an impact on confidentiality, integrity, and availability. CVE summarizes:

Kroki creates diagrams from textual descriptions. From 0.26.0 until 0.31.2, the optional Mermaid companion's mermaid/src/worker.js renders attacker-controlled flowchart image nodes in headless Chromium without a network request policy, even when KROKI_SAFE_MODE is set to secure. An actor who can submit Mermaid source and satisfy any authentication or authorization configured by the deployment can cause the companion to issue HTTP or HTTPS GET requests when requesting PNG output. Exploitation requires the Mermaid companion, PNG rendering through its headless Chromium process, a diagram-submission path available to the actor, and network reachability from the companion to the target. The demonstrated impact is limited to blind request reachability and possible state-changing GET endpoints; response exfiltration, cloud metadata access, port scanning, and access beyond the companion's network reachability are not established. This issue is fixed in version 0.31.2.

The advisory is available at github.com. This vulnerability is traded as CVE-2026-102356 since 09/29/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. Technical details are known, but there is no available exploit.

Upgrading to version 0.31.2 eliminates this vulnerability.

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Productinfo

Vendor

• Yuzutech

Name

• Kroki

Version

• 0.31.0
• 0.31.1

Website

• Product: https://github.com/yuzutech/kroki/

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