CVE-2026-2469: DirectoryTree ImapEngine RCE Vulnerability

CVE-2026-2469 Overview

CVE-2026-2469 is an IMAP command injection vulnerability affecting the DirectoryTree ImapEngine PHP package. Versions before 1.22.3 are vulnerable to improper neutralization of special elements in the id() function within ImapConnection.php. The vulnerability occurs due to inadequate escaping of user input before including it in IMAP ID commands, allowing attackers to inject arbitrary IMAP commands by manipulating input with quote characters (") or CRLF sequences (\r\n).

Critical Impact
Successful exploitation allows attackers to read or delete victim's emails, terminate active sessions, or execute any valid IMAP command on the victim's mailbox, potentially leading to complete mailbox compromise.

Affected Products

DirectoryTree ImapEngine versions prior to 1.22.3
Applications using the directorytree/imapengine PHP package with vulnerable versions
Any PHP application integrating the affected ImapConnection.php component

Discovery Timeline

2026-02-14 - CVE-2026-2469 published to NVD
2026-02-18 - Last updated in NVD database

Technical Details for CVE-2026-2469

Vulnerability Analysis

This vulnerability is classified as CWE-74 (Improper Neutralization of Special Elements in Output Used by a Downstream Component), commonly known as an injection vulnerability. The root issue stems from the id() function in ImapConnection.php failing to properly sanitize user-controlled input before incorporating it into IMAP protocol commands.

IMAP (Internet Message Access Protocol) commands follow a specific syntax where special characters like quotes and CRLF sequences have semantic meaning. When user input containing these characters is passed directly to IMAP commands without proper escaping, attackers can break out of the intended command structure and inject additional commands that the IMAP server will execute with the authenticated user's privileges.

The attack is network-accessible and requires only low privileges to execute, making it particularly dangerous in multi-tenant email applications or services where user input flows into IMAP operations.

Root Cause

The vulnerability exists because the id() function in ImapConnection.php does not properly escape or validate user-supplied input before embedding it into IMAP ID commands. The IMAP protocol interprets quote characters and CRLF sequences as command delimiters and terminators respectively. By injecting these special characters, an attacker can terminate the current command prematurely and inject additional malicious commands.

The fix, as documented in the GitHub Pull Request, implements proper input sanitization to neutralize these special characters before they reach the IMAP command construction logic.

Attack Vector

The attack is executed over the network and exploits the application's IMAP connection handling. An attacker with authenticated access can craft malicious input containing:

Quote characters ("): To break out of string literals in IMAP commands
CRLF sequences (\r\n): To terminate the current command and inject new commands

When the vulnerable id() function processes this malicious input, the injected characters are passed directly to the IMAP server, which interprets them as command syntax rather than data. This allows the attacker to execute arbitrary IMAP commands such as FETCH, STORE, EXPUNGE, or LOGOUT, enabling email theft, deletion, or session termination.

For detailed technical analysis of the vulnerability mechanism, refer to the security researcher's Gist and the Snyk vulnerability advisory.

Detection Methods for CVE-2026-2469

Indicators of Compromise

Unexpected IMAP protocol errors or malformed command responses in application logs
Suspicious email access patterns including bulk read or delete operations
Abnormal session terminations for authenticated users
IMAP server logs showing unexpected command sequences or injection attempts containing quote characters or CRLF patterns

Detection Strategies

Monitor IMAP traffic for command injection patterns including embedded quotes or CRLF sequences in ID commands
Implement application-level logging to capture all inputs to the id() function before IMAP command execution
Deploy web application firewalls (WAF) configured to detect injection patterns in request parameters destined for email functionality
Use dependency scanning tools to identify vulnerable versions of directorytree/imapengine in your codebase

Monitoring Recommendations

Enable detailed IMAP server logging to capture full command sequences and identify anomalous patterns
Configure alerts for unusual email operations such as mass deletions or unauthorized access to mailboxes
Implement application performance monitoring (APM) to detect unexpected IMAP connection behavior
Regularly audit Composer dependencies using composer audit to identify known vulnerable packages

How to Mitigate CVE-2026-2469

Immediate Actions Required

Upgrade DirectoryTree ImapEngine to version 1.22.3 or later immediately
Review application code for any custom implementations that may bypass the patched id() function
Audit recent IMAP activity logs for signs of exploitation
Consider temporarily disabling IMAP ID functionality if upgrade is not immediately possible

Patch Information

The vulnerability has been addressed in DirectoryTree ImapEngine version 1.22.3. The fix implements proper input sanitization to escape quote characters and CRLF sequences before including user input in IMAP commands. The specific fix can be reviewed in the GitHub commit.

Organizations should update their composer.json to require the patched version and run composer update directorytree/imapengine to apply the fix.

Workarounds

Implement application-level input validation to strip or reject quote characters and CRLF sequences from any input that may reach IMAP operations
Deploy network-level filtering to inspect and sanitize IMAP traffic for injection patterns
Restrict IMAP functionality to trusted users only until the patch can be applied
Consider implementing a wrapper function that sanitizes inputs before calling the vulnerable id() function

bash

# Update to patched version via Composer
composer require "directorytree/imapengine:>=1.22.3"
composer update directorytree/imapengine

# Verify installed version
composer show directorytree/imapengine | grep versions