EUVD-2026-56240
GHSA-vj3w-h7v3-5rpr
Severity by source
AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
AV:L because the target is a local dev server; PR:N because the dev server has no authentication; UI:R because DNS rebinding requires the developer to visit an attacker page.
Primary rating from Vendor (cisa-cg).
CVSS VectorVendor: cisa-cg
Lifecycle Timeline
3DescriptionCVE.org
Genkit does not properly validate host request headers. Any host on the developer's network, and any website the developer visits (via DNS rebinding), can reach POST /api/runAction on the Dev UI server (default port 4000) and execute any registered Genkit action and read the result. Fixed on 2026-06-18.
AnalysisAI
DNS rebinding and local-network exposure in the Genkit Developer UI server (default port 4000) allows any attacker-controlled website visited by the developer, or any host on the developer's local network, to invoke POST /api/runAction and execute arbitrary registered Genkit actions, reading full results. The root cause is absent Host header validation combined with the server binding to all network interfaces rather than loopback only. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | The Genkit Dev UI server must be actively running on the developer's machine (it runs during local development sessions, not in production). … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The official CVSS 3.1 vector (AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H) scores 7.8 and is consistent with the attack model: the target is a local dev server (AV:L), attack complexity is low once the developer visits a malicious page (AC:L), no authentication is required on the dev server (PR:N), but developer interaction is mandatory - the developer must visit an attacker website for DNS rebinding, or the attacker must already be on the same local network (UI:R). … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | Full exploit scenario with step-by-step reproduction available after sign-in. |
| Remediation | Update to a Genkit release incorporating the fix from PR #5587 (merged 2026-06-18); this is the primary and complete remediation as confirmed by the upstream patch. … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours, identify all development environments running Google Genkit Developer UI (default port 4000) and immediately restrict network access by configuring the server to bind to loopback only (127.0.0.1:4000) or isolating from untrusted networks until patched. …
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External POC / Exploit Code
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