---
id: "CVE-2026-115785"
kind: "vulnerability"
aliases: ["CVE-2026-115785"]
title: "Zimbra: authenticated users can inject SMTP commands and send mail"
severity: "medium"
cvss: 4.3
epss: 0.00979
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["email", "package", "self-hosted", "zimbra"]
not_affected_if: ["auth-required"]
published_at: "2026-10-23T14:17:52+00:00"
first_seen_at: "2026-10-23T21:57:34+00:00"
updated_at: "2026-10-25T12:38:50+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-115785", "first_seen_at": "2026-10-23T21:57:34+00:00"}, {"source": "epss", "url": "https://api.first.org/data/v1/epss?cve=CVE-2026-115785", "first_seen_at": "2026-10-25T12:38:50+00:00"}]
---

# Zimbra: authenticated users can inject SMTP commands and send mail

Zimbra Collaboration Suite's data-source testing feature does not strip CR/LF characters from the email address placed in an SMTP envelope command. An authenticated user with account options enabled can smuggle extra SMTP commands and send mail with attacker-chosen recipients, headers and body.

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

## How to check

- Check the installed Zimbra version with `su - zimbra -c "zmcontrol -v"` and compare against the fixed release listed in the advisory.
- Confirm whether account options and data-source testing are enabled for users, and whether the SMTP service accepts pipelined transactions.

## Fix

- Upgrade Zimbra Collaboration Suite to a release newer than `10.1.20`; the sources do not name the exact fixed version.
- Until patched, unknown whether restricting account option changes is a workable mitigation; the sources do not say.

## Timeline

- 2026-10-23T21:57:34+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-115785
- 2026-10-25T12:38:50+00:00 epss https://api.first.org/data/v1/epss?cve=CVE-2026-115785

## From the sources

An SMTP command injection vulnerability in the data-source testing functionality of Zimbra Collaboration Suite (ZCS) allows an ordinary authenticated user with account options enabled to inject CR/LF into the emailAddress inserted into an SMTP envelope command by a JSON SOAP request. After a successful preliminary POP3 or IMAP login, Zimbra sends the injected commands to the selected SMTP service. If that service accepts the pipelined transaction, the attacker can submit mail with attacker-selected recipients, headers and body content without victim interaction. The vulnerable command-construction path is present in ZCS 10.1.16 and 10.1.20.

---

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