# CVE-2026-27860: If auth_username_chars is empty, it is possible to inject arbitrary LDAP filter to Dovecot's LDAP authentication. This…

Source: https://junglewise.ai/threats/cve-2026-27860-if-auth-username-chars-is-empty-it-is-possible-to-inject  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-03-27  
License: CC BY 4.0 with a link back

CVE-2026-27860 · Severity: low · CVSS 3.7 · Published 2026-03-27

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.

Technologies: [Dovecot](https://junglewise.ai/threats/technologies/dovecot), [Open-Xchange Dovecot](https://junglewise.ai/threats/technologies/open-xchange-dovecot). Vendors: [Dovecot](https://junglewise.ai/threats/vendors/dovecot), [Open-Xchange](https://junglewise.ai/threats/vendors/open-xchange).

## Quick answers

**Is CVE-2026-27860 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-27860 being exploited in the wild.

**How severe is CVE-2026-27860?** Low severity, with a CVSS score of 3.7, published 27 March 2026.

**Which products and versions are affected?** Dovecot, Open-Xchange Dovecot. The advisory does not name versions.

**Is there a fix for CVE-2026-27860?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**Am I affected by CVE-2026-27860?** Check whether you run Dovecot or Open-Xchange Dovecot. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Affected products

- Dovecot
- Open-Xchange Dovecot

## Related threats

- [Dovecot ManageSieve denial of service via malformed pre-auth command](https://junglewise.ai/threats/cve-2026-33605-dovecot-managesieve-denial-of-service-via-malformed-pre-auth)
- [Open-Xchange Dovecot uncontrolled memory consumption in IMAP](https://junglewise.ai/threats/cve-2026-42006-open-xchange-dovecot-uncontrolled-memory-consumption-in-imap)
- [Open-Xchange Dovecot improper access control in IMAP SETACL](https://junglewise.ai/threats/cve-2026-40020-open-xchange-dovecot-improper-access-control-in-imap-setacl)
- [Open-Xchange Dovecot CPU limit bypass in Sieve scripts](https://junglewise.ai/threats/cve-2026-40016-open-xchange-dovecot-cpu-limit-bypass-in-sieve-scripts)
- [Open-Xchange Dovecot SCRAM TLS channel binding spoofing](https://junglewise.ai/threats/cve-2026-33603-open-xchange-dovecot-scram-tls-channel-binding-spoofing)