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CVE-2026-102356— Kroki Mermaid companion SSRF via flowchart image URLs

Quick assessment

Affected
yuzutech kroki
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Kroki 可根据文本描述生成图表。在 0.26.0 至 0.31.2 版本中，可选的 Mermaid 辅助组件（位于 mermaid/src/worker.js）会在无网络请求策略的情况下，通过无头（headless）Chromium 渲染由攻击者控制的流程图图像节点，即使已将 KROKI_SAFE_MODE 设置为安全模式。任何能够提交 Mermaid 源码并满足部署所配置的认证或授权要求的攻击者，均可在请求 PNG 输出时，诱导该辅助组件向目标发起 HTTP 或 HTTPS GET 请求。 利用此漏洞需要满足

CVSS 5.0 · Medium

Affected Version Matrix 1

VendorProduct Version RangeStatus
yuzutech kroki >= 0.26.0, < 0.31.2 affected
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I. Basic Information for CVE-2026-102356

Vulnerability Information
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Vulnerability Title
Kroki Mermaid companion SSRF via flowchart image URLs
Source: CVE Program / CVE List V5
Vulnerability Description
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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:N/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
服务端请求伪造(SSRF)
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
yuzutech kroki >= 0.26.0, < 0.31.2 -

II. Public POCs for CVE-2026-102356

# POC Description Source Link Shenlong Link
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III. Intelligence Information for CVE-2026-102356

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Other References for CVE-2026-102356 (3)

IV. Related Vulnerabilities

Same product: kroki
Same vendor: yuzutech
Same weakness: CWE-918