Executive Summary
Sand Security's WriteOut: a patched one-click session isolation flaw in Writer's enterprise AI platform let agent previews leak session tokens across tenants.
What Happened
Cybersecurity researchers have disclosed details of a now-patched critical session isolation vulnerability in Writer, an enterprise generative artificial intelligence (AI) platform, that could result in cross-tenant compromise. The one-click vulnerability has been codenamed WriteOut by the Sand Security Research team. "An outsider could go from having no access to taking over any Writer AI
Affected Products
- Writer AI
Vulnerability / Attack Technique
Cross-tenant session token leak in an AI platform
Technical Mechanism
As reported, agent previews were not isolated per tenant.
AI Security Category
LLM02:2025 Sensitive Information Disclosure
Relevant Frameworks
RealGround Analysis
Multi-tenant AI platforms must isolate agent output. RealGround analysis: ask AI vendors how tenants are separated.
Recommended Controls
- Confirm the Writer fix is applied
- Review AI vendor tenant isolation
Related RealGround Service
AI Security Readiness Assessment · or start with the free AI Agent Security Scanner.
Sources
thehackernews.com: https://thehackernews.com/2026/07/writer-ai-flaw-could-let-agent-previews.html
Summary and analysis written by RealGround from the source above; last updated 2026-10-18.