CVE-2025-59028: dovecot Improper Input Validation
Vulnerability summary
CVE-2025-59028 is a high (CVSS 7.5) Improper Input Validation vulnerability in dovecot. EPSS estimates a 0.45% chance of exploitation in the next 30 days, higher than 37.5% of scored vulnerabilities.
Advisory lineage
Upstream 0 · Downstream 4 · Related 5Timeline
- 27-03-2026PublishedVulnerability first disclosed.
- 27-03-2026Last modifiedVulnerability information updated.
Description
When sending invalid base64 SASL data, login process is disconnected from the auth server, causing all active authentication sessions to fail. Invalid BASE64 data can be used to DoS a vulnerable server to break concurrent logins. Install fixed version or disable concurrency in login processes (heavy perfomance penalty on large deployments). No publicly available exploits are known.
CVSS metrics
5 scores · 5 sources · 1 version- CVE.orgCNA5.3MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:LDiffers
- OSV · AlpineEcosystem advisory · calculated7.5HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- OSV · UbuntuEcosystem advisory · calculated7.5HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- OSV · DebianEcosystem advisory · calculated7.5HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS trend
Probability
0.45%
Chance of exploitation in the next 30 days
Percentile
38%
Versus all other CVEs
30-day change
0.00 pp
From 0.45% on 20-09-2026
Known exploited
Compare KEV catalogsNot in any of the 3 tracked catalogs.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root causeAffected systems
Alpine1 product
- dovecot< 2.4.3-r0
Debian1 product
- dovecot< 1:2.4.1+dfsg1-6+deb13u4 | < 1:2.4.3+dfsg1-1
Dovecot1 product
- dovecot< 2.4.3
Open-xchange1 product
- dovecot< 3.1.2
Open-xchange gmbh1 product
- ox dovecot pro≤ 3.1.0 | ≤ 2.4.0
Ubuntu1 product
- dovecot< 1:2.4.1+dfsg1-5ubuntu4.1
6 vendors · 6 products
