CVE-2026-128334

Description

listmonk 6.2.0 before 7.0.0-beta.2 contains a missing authentication vulnerability that allows unauthenticated attackers to submit Azure Event Grid bounce webhooks when no shared secret is configured. Attackers can POST forged EmailDeliveryReportReceived events with Bounced status to /webhooks/service/azure to blocklist, unsubscribe, or delete arbitrary subscribers.

References

• https://github.com/biofool/listmonk/issues/5
• https://github.com/knadh/listmonk/blob/v7.0.0-beta.1/internal/bounce/webhooks/azure.go#L141-L149
• https://github.com/knadh/listmonk/commit/0c155bd2663d9ec8053ac0d1ab63f021fbb5a0dc
• https://github.com/knadh/listmonk/releases/tag/v7.0.0-beta.2
• https://www.vulncheck.com/advisories/listmonk-6.2.0-before-7.0.0-beta.2-missing-authentication-via-azure-bounce-webhook