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

CVE-2026-27860 is fixed in 17 products on 1 platform, first by DEBIAN-CVE-2026-27860, released March 27, 2026. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2026-27860
- Priority: Routine
- CVSS: 5.3 (medium)
- EPSS: 0.0030
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Mar 26, 2026

## 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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | dovecot Debian 13.5 (trixie) | 1:2.4.1+dfsg1-6+deb13u4 | [DEBIAN-CVE-2026-27860](https://patchblox.com/security/data/fix/linux/debian-cve-2026-27860.md) | Mar 27, 2026 |
| Linux | dovecot Debian 14 | 1:2.4.3+dfsg1-1 | [DEBIAN-CVE-2026-27860](https://patchblox.com/security/data/fix/linux/debian-cve-2026-27860.md) | Mar 27, 2026 |
| Linux | dovecot-auth-lua Ubuntu 25.10 (questing) | 1:2.4.1+dfsg1-5ubuntu4.1 | [dovecot-auth-lua 1:2.4.1+dfsg1-5ubuntu4.1](https://patchblox.com/security/data/fix/linux/ubuntu-questing-dovecot-auth-lua-1-2.4.1-dfsg1-5ubuntu4.1.md) | Apr 15, 2026 |
| Linux | dovecot-core Ubuntu 25.10 (questing) | 1:2.4.1+dfsg1-5ubuntu4.1 | [dovecot-core 1:2.4.1+dfsg1-5ubuntu4.1](https://patchblox.com/security/data/fix/linux/ubuntu-questing-dovecot-core-1-2.4.1-dfsg1-5ubuntu4.1.md) | Apr 15, 2026 |
| Linux | dovecot-flatcurve Ubuntu 25.10 (questing) | 1:2.4.1+dfsg1-5ubuntu4.1 | [dovecot-flatcurve 1:2.4.1+dfsg1-5ubuntu4.1](https://patchblox.com/security/data/fix/linux/ubuntu-questing-dovecot-flatcurve-1-2.4.1-dfsg1-5ubuntu4.1.md) | Apr 15, 2026 |
| Linux | dovecot-gssapi Ubuntu 25.10 (questing) | 1:2.4.1+dfsg1-5ubuntu4.1 | [dovecot-gssapi 1:2.4.1+dfsg1-5ubuntu4.1](https://patchblox.com/security/data/fix/linux/ubuntu-questing-dovecot-gssapi-1-2.4.1-dfsg1-5ubuntu4.1.md) | Apr 15, 2026 |
| Linux | dovecot-imapd Ubuntu 25.10 (questing) | 1:2.4.1+dfsg1-5ubuntu4.1 | [dovecot-imapd 1:2.4.1+dfsg1-5ubuntu4.1](https://patchblox.com/security/data/fix/linux/ubuntu-questing-dovecot-imapd-1-2.4.1-dfsg1-5ubuntu4.1.md) | Apr 15, 2026 |
| Linux | dovecot-ldap Ubuntu 25.10 (questing) | 1:2.4.1+dfsg1-5ubuntu4.1 | [dovecot-ldap 1:2.4.1+dfsg1-5ubuntu4.1](https://patchblox.com/security/data/fix/linux/ubuntu-questing-dovecot-ldap-1-2.4.1-dfsg1-5ubuntu4.1.md) | Apr 15, 2026 |
| Linux | dovecot-lmtpd Ubuntu 25.10 (questing) | 1:2.4.1+dfsg1-5ubuntu4.1 | [dovecot-lmtpd 1:2.4.1+dfsg1-5ubuntu4.1](https://patchblox.com/security/data/fix/linux/ubuntu-questing-dovecot-lmtpd-1-2.4.1-dfsg1-5ubuntu4.1.md) | Apr 15, 2026 |
| Linux | dovecot-managesieved Ubuntu 25.10 (questing) | 1:2.4.1+dfsg1-5ubuntu4.1 | [dovecot-managesieved 1:2.4.1+dfsg1-5ubuntu4.1](https://patchblox.com/security/data/fix/linux/ubuntu-questing-dovecot-managesieved-1-2.4.1-dfsg1-5ubuntu4.1.md) | Apr 15, 2026 |
| Linux | dovecot-mysql Ubuntu 25.10 (questing) | 1:2.4.1+dfsg1-5ubuntu4.1 | [dovecot-mysql 1:2.4.1+dfsg1-5ubuntu4.1](https://patchblox.com/security/data/fix/linux/ubuntu-questing-dovecot-mysql-1-2.4.1-dfsg1-5ubuntu4.1.md) | Apr 15, 2026 |
| Linux | dovecot-pgsql Ubuntu 25.10 (questing) | 1:2.4.1+dfsg1-5ubuntu4.1 | [dovecot-pgsql 1:2.4.1+dfsg1-5ubuntu4.1](https://patchblox.com/security/data/fix/linux/ubuntu-questing-dovecot-pgsql-1-2.4.1-dfsg1-5ubuntu4.1.md) | Apr 15, 2026 |
| Linux | dovecot-pop3d Ubuntu 25.10 (questing) | 1:2.4.1+dfsg1-5ubuntu4.1 | [dovecot-pop3d 1:2.4.1+dfsg1-5ubuntu4.1](https://patchblox.com/security/data/fix/linux/ubuntu-questing-dovecot-pop3d-1-2.4.1-dfsg1-5ubuntu4.1.md) | Apr 15, 2026 |
| Linux | dovecot-sieve Ubuntu 25.10 (questing) | 1:2.4.1+dfsg1-5ubuntu4.1 | [dovecot-sieve 1:2.4.1+dfsg1-5ubuntu4.1](https://patchblox.com/security/data/fix/linux/ubuntu-questing-dovecot-sieve-1-2.4.1-dfsg1-5ubuntu4.1.md) | Apr 15, 2026 |
| Linux | dovecot-solr Ubuntu 25.10 (questing) | 1:2.4.1+dfsg1-5ubuntu4.1 | [dovecot-solr 1:2.4.1+dfsg1-5ubuntu4.1](https://patchblox.com/security/data/fix/linux/ubuntu-questing-dovecot-solr-1-2.4.1-dfsg1-5ubuntu4.1.md) | Apr 15, 2026 |
| Linux | dovecot-sqlite Ubuntu 25.10 (questing) | 1:2.4.1+dfsg1-5ubuntu4.1 | [dovecot-sqlite 1:2.4.1+dfsg1-5ubuntu4.1](https://patchblox.com/security/data/fix/linux/ubuntu-questing-dovecot-sqlite-1-2.4.1-dfsg1-5ubuntu4.1.md) | Apr 15, 2026 |
| Linux | dovecot-submissiond Ubuntu 25.10 (questing) | 1:2.4.1+dfsg1-5ubuntu4.1 | [dovecot-submissiond 1:2.4.1+dfsg1-5ubuntu4.1](https://patchblox.com/security/data/fix/linux/ubuntu-questing-dovecot-submissiond-1-2.4.1-dfsg1-5ubuntu4.1.md) | Apr 15, 2026 |
| Linux | dovecot24 opensuse-leap 16.0 | 2.4.3-160000.1.1 | [OPENSUSE-SU-2026:20554-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-20554-1.md) | Apr 16, 2026 |
| Linux | dovecot24 sles 16.0 | 2.4.3-160000.1.1 | [SUSE-SU-2026:21208-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-21208-1.md) | Apr 16, 2026 |

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Data as of 2026-11-09T07:25:28Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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