CVE-2026-27860

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.

CVSS 3.1

5.3CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

EPSS

0.3% chance of exploitation in the next 30 days; higher than 22% of CVEs (scores of 2026-10-25)

CWE

CWE-90

Published

2026-03-27

Modified

2026-10-26

Record from

the NVD, synced 2026-10-26

Affected

• dovecot:dovecot
• open-xchange:dovecot

References

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

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