Cloudflare AI service cache error: 155 GLM-5.3 responses mixed in others' data

Cloudflare published the findings of its investigation into the data leak at its Workers AI: between August 27 and September 9, the GLM-5.3 model had a total of 155 responses that mixed in other customers' data; the fix was completed on September 9; other models were unaffected, and no evidence of deliberate exploitation was found. The incident stemmed from Cloudflare's deployment configuration and a program vulnerability in the open-source inference software SGLang: the GLM-5.3 input limit was set to about 1.05 million text units, but the GPU cache handling the input could hold only about 680,000; when input exceeded the cache capacity, SGLang did not reject the request as designed, causing responses to mix in content left in the KV cache by other customers. Gadi Evron, a researcher at the security firm Knostic, reported it on September 8; Cloudflare reproduced the problem the next day with two accounts, suspended the model service, and restored it the same day after the fix. Cloudflare acknowledged that before launch it knew the cache capacity did not match the input limit, but at the time it only checked response status and performance; SGLang users had reported the related vulnerability as early as July.