Flowise versions prior to 3.1.4 expose an unauthenticated denial of service vulnerability in the /api/v1/text-to-speech/abort endpoint. The endpoint accepts user-supplied chatflowId and chatId without verifying the caller’s ownership of the associated resources. An attacker can submit crafted requests and terminate active chatflow predictions for any user, leading to targeted service disruption and loss of availability for the affected chat sessions.

FlowiseAI’s Flowise product is affected. All releases before version 3.1.4 are vulnerable. Clients running these versions should treat the backend as a public-facing service until the vulnerability is remedied (inferred).

The CVSS score of 6.3 places this issue in the medium severity range. EPSS data is not available and the vulnerability is not listed in the CISA KEV catalog, suggesting lower exploitation activity at present. The attack vector is inferred to be unauthenticated traffic over the network, as no authentication is required to reach the endpoint. An attacker with network access to the Flowise instance can issue HTTP requests to the abort endpoint and force the termination of any user’s active prediction.