CVE-2026-33603
Publication date 12 May 2026
Last updated 5 June 2026
Ubuntu priority
Description
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 communications between Dovecot and client as MITM proxy. Install fixed version. No publicly available exploits are known.
Status
| Package | Ubuntu Release | Status |
|---|---|---|
| dovecot | 26.04 LTS resolute |
Fixed 1:2.4.2+dfsg1-3ubuntu2.1
|
| 25.10 questing |
Fixed 1:2.4.1+dfsg1-5ubuntu4.2
|
|
| 24.04 LTS noble |
Fixed 1:2.3.21+dfsg1-2ubuntu6.5
|
|
| 22.04 LTS jammy |
Fixed 1:2.3.16+dfsg1-3ubuntu2.9
|
|
| 20.04 LTS focal |
Needs evaluation
|
|
| 18.04 LTS bionic |
Needs evaluation
|
|
| 16.04 LTS xenial |
Needs evaluation
|
|
| 14.04 LTS trusty |
Needs evaluation
|
Severity score breakdown
CVSS version: CVSS v3.0
Base score
6.8 · Medium
Vector: CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
References
Related Ubuntu Security Notices (USN)
- USN-8365-1
- Dovecot vulnerabilities
- 2 June 2026