CVE-2026-33603
Dovecot ≤ 2.4.4
Raw vector
CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:NSummary
CVE-2026-33603 is a medium-severity Resource Injection (CWE-99) vulnerability in Dovecot Dovecot. Its CVSS base score is 6.8 (Medium).
Operationally, exploitation aligns with the MITRE ATT&CK technique Adversary-in-the-Middle (T1557); ranked at the 13th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified map to SC-23 (Session Authenticity) and SC-8 (Transmission Confidentiality and Integrity) — see the control section below for these in your framework.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-29468
Vulnerability Data
Attacker can use a specially crafted base64 exchange between Dovecot and Client to fake SCRAM TLS channel binding. This requires that the attacker is able to position itself between Dovecot and the client connection. If successful, the attacker can eavesdrop…
more
communications between Dovecot and client as MITM proxy. Install fixed version. No publicly available exploits are known.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
CVE enables active MITM positioning via forged SCRAM TLS channel binding to eavesdrop on Dovecot client sessions, directly mapping to Adversary-in-the-Middle.
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
Mitigating Controls (NIST 800-53 r5) AI
Enforces cryptographic protection of session traffic (confidentiality+integrity) so that a successful fake channel-binding MITM attack cannot eavesdrop or tamper with Dovecot client exchanges.
Requires mechanisms that bind authentication to the underlying TLS channel, directly countering the SCRAM channel-binding bypass described in the CVE.
Mandates timely installation of the vendor-supplied patch that corrects the base64 exchange flaw allowing forged channel bindings.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Secure SDLC practices directly require input validation and sanitization that prevent resource-identifier injection flaws.
Least-privilege access policy and enforcement limits damage from injected resource identifiers even when input validation is absent.
Network segmentation and unauthorized-access controls reduce the blast radius of successful resource injection.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Security testing can detect resource-injection flaws but does not itself implement preventive controls.
Secure SDLC mandates input validation and resource-identifier sanitization that directly prevents resource injection.
Application security requirements explicitly call for controls on external identifiers used to access resources.
Secure architecture principles reduce attack surface for resource injection but do not prescribe identifier validation.
Secure coding standards require strict validation and whitelisting of all resource identifiers before use.
Information-access-restriction policies limit which resources can be referenced, indirectly reducing injection impact.