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CVE-2026-70558 – Unauthenticated Arbitrary File Write (RCE) – DataLinkDC Dinky v0 through v1.2.5

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Summary

CVE-2026-70558 is a critical unauthenticated arbitrary file write vulnerability (CWE-434 / CWE-22) in DataLinkDC Dinky, the open-source real-time data development platform. The POST /download/uploadFromRsByLocal endpoint writes attacker-supplied files to attacker-controlled paths, guarded only by a hardcoded token shipped in every deployment, enabling remote code execution. It carries a CVSS v3.1 base score of 9.8 (Critical).

Technical details

  • Root cause: The DownloadController handler for POST /download/uploadFromRsByLocal accepts an unvalidated path parameter and passes it directly to file write operations with no path canonicalization or prefix validation.
  • Authentication bypass: The route is annotated @SaIgnore and /download/** is excluded from the Sa-Token interceptor. The only guard is a header equality check against the dinkyToken value, whose default (efda1551-7958-4e0f-80a8-dfd107df3e38) is hardcoded in source and distributed with every installation, so it provides no effective protection.
  • Trigger conditions: An attacker with network access to the Dinky HTTP port (8888 by default) sends a multipart request supplying the hardcoded token header and a crafted path.
  • Attack vector: Network; no privileges and no user interaction required.
  • Impact: Arbitrary file write as the Dinky service account. Demonstrated escalation to code execution — overwriting /opt/dinky/config/static/index.html served attacker JavaScript to admin browsers, and writing a .class file into the application classpath executed code. Default Docker deployments run with chmod 777 on /opt/dinky, making the classpath, launch scripts, and static assets writable.

Affected software

  • DataLinkDC Dinky versions v0 through v1.2.5 (inclusive), including the development branch.

Severity

  • CVSS v3.1: 9.8 (Critical) — CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
  • CVSS v4.0: 9.3 (Critical) — CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

Mitigation and recommended actions

  • Immediate: No patched release existed at the time of disclosure. Monitor the vendor for an official fixed version and upgrade as soon as it is published.
  • If no patch:
    • Restrict network access to the Dinky HTTP port (8888 by default); do not expose it to untrusted networks.
    • Change the dinkyToken value away from the hardcoded default.
    • Block /download/** (and /api/sysConfig/getAll) for unauthenticated clients at a reverse proxy.
    • Tighten filesystem permissions; avoid chmod 777 on /opt/dinky.
    • Rotate credentials stored in the Settings Center (LDAP, object-storage keys, scheduler tokens).

How IONIX identifies potentially affected assets

IONIX matches the following signals against data already collected when it crawled the asset; identifying the technology sends no request beyond that crawl.

  • Page title: Dinky
  • Raw response body: /scripts/loading.js, dinky.svg
  • Favicon fingerprint: -1020504139

References

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