OX Dovecot Pro EUVD-2026-29468

The attacker must achieve and maintain a network-adjacent MITM position (AV:A) between the client and Dovecot server, meaning layer-2 or layer-3 control. The attack targets SCRAM authentication with TLS channel binding enabled; if channel binding is disabled or a different auth mechanism is used, the vulnerability does not apply. High complexity (AC:H) suggests the attacker must possess knowledge of SCRAM protocol specifics and the ability to forge mathematically or cryptographically valid base64 exchanges that match the TLS session context. No authentication is required from the attacker (PR:N), and no user interaction is required (UI:N) - the attack operates entirely on protocol messages.

CVSS 6.8 with AV:A/AC:H reflects moderate risk: the attacker vector is adjacent (local network or compromised intermediate host), complexity is high (requires precise crafting and positioning), but impact is severe (full confidentiality and integrity compromise). EPSS data is not provided, limiting exploitation probability estimation. No CISA KEV status is indicated, suggesting active exploitation has not been confirmed by federal authorities at time of disclosure. The absence of public POC code slightly lowers immediate operational risk, but the attack is technically feasible and would not require elevated privileges. Real-world risk depends heavily on network topology: attacks are most viable in scenarios with wireless networks, shared infrastructure (cloud, hosting), or compromised intermediaries. Organizations with air-gapped or tightly controlled mail server networks face lower practical risk despite the vulnerability's technical severity.

An attacker on a shared network (e.g., coffee shop WiFi, corporate guest network, or compromised ISP infrastructure) intercepts SCRAM authentication handshakes between a mail client and Dovecot. By crafting malicious base64 SCRAM messages that forge channel binding data, the attacker convinces both parties to complete authentication despite the attacker's MITM position. Once authenticated, the attacker proxies encrypted mail traffic, decrypting and reading all messages. High attack complexity reflects the requirement to craft valid base64 structures and timing - this is not a simple sniffing attack.