OpenAI Expands Daybreak With GPT-5.5-Cyber to Help Defenders Patch Security Flaws

OpenAI says it is expanding its Daybreak initiative by releasing an improved trusted version of GPT-5.5-Cyber for defenders to help analyze large codebases, validate security issues, and generate/test patches. It is also updating the Codex Security plugin to accelerate vulnerability discovery and patch workflows, including triaging findings from scanners and advisories. The article highlights that Daybreak efforts have been associated with vulnerabilities such as CVE-2026-47729 (Squidbleed) and CVE-2026-8390 (WebAssembly in Mozilla Firefox), underscoring why faster remediation matters as frontier AI can also shorten the time between disclosure and exploitation.