CVE-2026-102356
Kroki Mermaid companion SSRF via flowchart image URLs
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.
Fixes and workarounds
Fix
io.kroki:kroki-server (maven): GitHub reports patched versions 0.31.2. Check the advisory for the affected release branch.
Source: GitHub GHSA-px99-rjv4-49g8Affected products and versions
| Product | Versions | Authority |
|---|---|---|
| kroki yuzutech |
>= 0.26.0, < 0.31.2 (affected) | CNA: GitHub_M |
io.kroki:kroki-serverio.kroki:kroki-server
maven |
>= 0.26.0, <= 0.31.1 (affected, GitHub advisory range) | GitHub GHSA-px99-rjv4-49g8 |
Version ranges are source assertions. Check the vendor advisory and your installed configuration before determining exposure.
CVSS assessments
| Version / score | Vector | Authority |
|---|---|---|
| 3.1 / 5.0 medium |
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:N/A:N | CNA: GitHub_M |
| 3.1 / 5.0 medium |
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:N/A:N | NVD: [email protected] |
Exploit evidence
No exploit evidence in collected sources. This is not proof of no exploitation.
References
- https://github.com/yuzutech/kroki/security/advisories/GHSA-px99-rjv4-49g8CNA: GitHub_M · x_refsource_CONFIRM
- https://github.com/yuzutech/kroki/commit/428ea380bc7db9da5c7947f908851c8461d51f82CNA: GitHub_M · x_refsource_MISC
- https://github.com/yuzutech/kroki/releases/tag/v0.31.2CNA: GitHub_M · x_refsource_MISC
- https://github.com/yuzutech/kroki/commit/428ea380bc7db9da5c7947f908851c8461d51f82[email protected]
- https://github.com/yuzutech/kroki/releases/tag/v0.31.2[email protected]
- https://github.com/yuzutech/kroki/security/advisories/GHSA-px99-rjv4-49g8[email protected]
- https://github.com/yuzutech/kroki/security/advisories/GHSA-px99-rjv4-49g8GitHub Security Advisories · advisory
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