Cloudflare Workers Spectre Attack Leaks JWT From Co-Located Worker at 12 Bits/Second

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Cloudflare Workers Spectre Attack Leaks JWT From Co-Located Worker at 12 Bits/Second

Thehackernews • August 19, 2026

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This article is one source in a clustered incident — the cluster page carries the summary, timeline and every other outlet covering it.

Cloudflare Workers Vulnerability Exploited by Faster Spectre Attack Researchers demonstrated a Spectre-class side-channel attack against Cloudflare Workers, achieving JWT exfiltration at 12 bits per second, 360 times faster than previous methods. This attack exploited a feature in Cloudflare's infrastructure and was validated in a live production environment. The research involved teams from Cloudflare, Graz University of Technology, and the University of Edinburgh, confirming no evidence of exploitation in the wild. Cloudflare has since enhanced its Dynamic Process Isolation (DyPrIs) and integrated Memory Protection Keys (MPK) to mitigate the vulnerability. The attack's core relied on speculative type confusion in V8, Google's JavaScript engine. Despite the improvements, the findings indicate that Spectre attacks continue to evolve and pose a significant risk in cloud environments. 5 sources 68

Extracted Entities

Attack Types (1)

CWE Weaknesses (1)

CWE-200 - Exposure of Sensitive Information

Platforms (1)

Cloudflare Workers

Vulnerabilities (1)