Vulnerability · Published Mar 27, 2026 · Assigned by OX

CVE-2026-27860

Low 3.7

In plain English

A low-severity security flaw in OX Dovecot Pro from Open-Xchange GmbH. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 23% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)3.7Low

Exploit odds (30 days)0.3%top 77.5% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official description

If auth_username_chars is empty, it is possible to inject arbitrary LDAP filter to Dovecot's LDAP authentication. This leads to potentially bypassing restrictions and allows probing of LDAP structure. Do not clear out auth_username_chars, or install fixed version. No publicly available exploits are known.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
Alpine:v3.23	dovecot	2.4.3-r0	ALPINE-CVE-2026-27860
Alpine:v3.24	dovecot	2.4.3-r0	ALPINE-CVE-2026-27860
Debian:13	dovecot	1:2.4.1+dfsg1-6+deb13u4	DEBIAN-CVE-2026-27860
Debian:14	dovecot	1:2.4.3+dfsg1-1	DEBIAN-CVE-2026-27860
Ubuntu:25.10	dovecot	1:2.4.1+dfsg1-5ubuntu4.1	UBUNTU-CVE-2026-27860

Affected products (as reported)

Vendor	Product	Versions
Open-Xchange GmbH	OX Dovecot Pro	0 – through 3.1.00 – through 2.4.0

Weakness: CWE-90 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N

References

https://documentation.open-xchange.com/dovecot/security/advisories/csaf/2026/oxdc-adv-2026-0001.json vendor-advisory