CVE-2026-102356 · Other
NO FIX YET · SEE WHAT TO DO
Kroki's optional Mermaid companion renders attacker-supplied flowchart image nodes in headless Chromium without a request policy, even when safe mode is set. An actor who can submit Mermaid source can make the companion issue HTTP or HTTPS GET requests, with the demonstrated impact limited to blind request reachability and possibly state-changing GET endpoints.
first public Jul 27, 2026 · 1 source
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Deployments that run the optional Kroki Mermaid companion, render PNG output through its headless Chromium, and let users submit Mermaid source. The companion must also have network reachability to internal targets for the request to matter. Deployments without the Mermaid companion or without PNG rendering are not in the stated exposure path.
Not affected if isolated-network, no-mermaid-companion, no-png-rendering
Who cares docker, kroki, mermaid, self-hosted
0.31.2 or later.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.
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