---
id: "CVE-2026-113386"
kind: "vulnerability"
aliases: ["CVE-2026-113386"]
title: "Roundcube Webmail: CRLF in mail uid lets authenticated users run IMAP commands"
severity: "high"
cvss: 7.1
epss: null
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["imap", "package", "roundcube", "self-hosted", "webmail"]
not_affected_if: ["no-untrusted-accounts", "versions-already-patched"]
published_at: "2026-10-20T05:16:54+00:00"
first_seen_at: "2026-10-23T21:57:20+00:00"
updated_at: "2026-10-25T03:34:49+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-113386", "first_seen_at": "2026-10-23T21:57:20+00:00"}]
---

# Roundcube Webmail: CRLF in mail uid lets authenticated users run IMAP commands

Roundcube Webmail before 1.6.20 and 1.7.x before 1.7.5 does not strip CRLF sequences from the _uid parameter of the mail/headers and mail/viewsource actions. A logged-in user can inject arbitrary IMAP commands into the mail server session, which can read or change mail beyond their own view.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Check the installed Roundcube version in the footer, `CHANGELOG.md`, or `composer show roundcube/roundcubemail` where installed via Composer.
- Confirm whether any version is below `1.6.20` on the 1.6 line or below `1.7.5` on the 1.7 line.

## Fix

- Upgrade Roundcube Webmail to `1.6.20` or later on the 1.6 line, or to `1.7.5` or later on the 1.7 line.
- Until patched, restrict who can log in to the webmail interface.

## Timeline

- 2026-10-23T21:57:20+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-113386

## From the sources

Roundcube Webmail before 1.6.20 and 1.7.x before 1.7.5 are affected by IMAP command injection. A remote authenticated attacker can exploit this via CRLF sequences injected into the _uid parameter of the mail/headers and mail/viewsource actions to execute arbitrary IMAP commands.

---

_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_