More than a hundred technology, security and financial companies - including OpenAI, Anthropic, Google, Microsoft, CrowdStrike, Okta and Fortinet - published an open letter on August 27, 2026, calling on the private and public sectors to jump-start a coordinated defense against a coming wave of AI-enabled cyberattacks.
The warning
"In the coming months, AI-enabled cyber attacks will become far more widespread and sophisticated as models around the world become increasingly capable," the letter states. The signatories - which also include internet infrastructure providers and large U.S. banks - single out hospitals, water utilities, power grids and the internet's core plumbing as the sectors most at risk from AI-driven intrusions, extortion and supply-chain manipulation.
The "defenders' window"
The group frames the current moment as a narrow "defenders' window," a period where AI tools help security teams find and patch weaknesses faster than adversaries can weaponise them. That advantage closes, they argue, if defenders do not adopt AI at scale quickly. Recommendations for organisations include remediating high-risk vulnerabilities, retiring end-of-life systems and deploying AI to prioritise patching. For governments, the letter calls for coordination across local, national and international lines, expanded funding for essential services with limited security budgets, and free or subsidised access to defensive AI tools for hospitals, water utilities and small municipalities.
Context and reaction
The letter arrives against the backdrop of a busy month of AI security disclosures, including the Amazon Kiro prompt-injection flaw, the actively exploited Citrix NetScaler CVE-2026-8452, and the GitLab GraphQL code-injection zero-day. It also follows the UK AI Safety Institute's agentic red-teaming incident report earlier this month.
Notably absent from the initial signatory list are Amazon, Meta and Apple, though industry analysts expect additional firms to add their names in the coming days.
Reporting based on coverage from TechCrunch, Bloomberg, CNBC, Axios, Engadget and Gizmodo.