Security brief

ServiceNow fixed an AI-platform impersonation flaw before its public disclosure

REVIEW

CVE-2025-12420 could allow unauthenticated impersonation; self-hosted and specially configured customers needed to verify their updates.

Published 29 Oct 2026 · Material update 12 Jan 2026 — last time the underlying evidence changed · Evidence: high

What happened

ServiceNow’s January 2026 advisory describes CVE-2025-12420, which could let an unauthenticated attacker impersonate another user and perform that user’s permitted operations. The issue affected parts of Now Assist AI Agents and Virtual Agent API.

ServiceNow said it deployed fixes to most hosted instances on October 30, 2025, and provided updates for other customer configurations. At disclosure, it reported no known exploitation against customer instances.

The advisory lists fixed Now Assist branches beginning at 5.1.18 and 5.2.19, and Virtual Agent API branches at 3.15.2 and 4.0.4. Match the appropriate branch and customer configuration to the vendor’s guidance rather than assuming every hosted or self-hosted instance was updated identically.

Read the original source.

Next step

Verify the appropriate Store App or instance update for your deployment.

What remains unknown

Open question
The sources reviewed do not establish whether your deployment was exploited.

Source references

Technical details

CVE
CVE-2025-12420