CVE-2026-2469: 
PHP vulnerability analysis and mitigation

CVE-2026-2469 is an IMAP command injection vulnerability in the directorytree/imapengine PHP library, classified as Improper Neutralization of Special Elements in Output Used by a Downstream Component (CWE-74). It affects all versions of the package before 1.22.3 and was disclosed on February 14, 2026, with the underlying fix merged on February 3, 2026. The vulnerability exists in the id() function of ImapConnection.php, which fails to properly escape user input before embedding it in IMAP ID commands. It carries a CVSS v3.1 base score of 7.6 (High) and a CVSS v4.0 base score of 5.7 (Medium) (GitHub Advisory, Snyk).

The root cause is insufficient input sanitization in the id() function within src/Connection/ImapConnection.php. Prior to the fix, user-supplied values were concatenated directly into IMAP ID command tokens using '"'.$id.'" ' without escaping, allowing injection of quote characters (") or CRLF sequences (\r\n) to break out of the quoted string context and inject arbitrary IMAP commands. The fix, applied in commit 87fca56, replaces the raw concatenation with Str::escape($id) to properly sanitize input before inclusion in the command token (GitHub Commit, GitHub Advisory). A proof-of-concept demonstrating the injection technique is publicly available via a GitHub Gist credited to researcher Wan Amirul Hakim Wan Yuhainis (Snyk).

A low-privileged, authenticated attacker can exploit this vulnerability to inject and execute arbitrary valid IMAP commands against a victim's mailbox. Concrete consequences include unauthorized reading or deletion of emails, termination of the victim's IMAP session, and full control over IMAP operations for the compromised account. Availability impact is rated High, while confidentiality and integrity impacts are rated Low, reflecting the attacker's ability to disrupt mailbox access and exfiltrate or destroy email data (GitHub Advisory, Snyk).

A proof-of-concept exploit exists publicly, referenced in the GitHub Advisory and credited to researcher Wan Amirul Hakim Wan Yuhainis via a GitHub Gist. The CVSS v4.0 exploit maturity is rated "Proof of Concept." The EPSS score is approximately 0.023% (7th percentile), indicating a low but non-zero probability of active exploitation in the near term. There is no current evidence of in-the-wild exploitation, threat actor attribution, or inclusion in the CISA KEV catalog (GitHub Advisory, Snyk).

1. Identify target: Locate applications using directorytree/imapengine versions before 1.22.3 that pass user-controlled input to the id() function (e.g., via a web application that proxies IMAP ID parameters).
2. Obtain low-privilege credentials: Acquire valid credentials for the target IMAP-connected application — this vulnerability requires authentication.
3. Craft malicious ID parameter: Construct an input value containing a CRLF sequence (\r\n) or a quote character (") to break out of the quoted string in the IMAP ID command. For example, a version field set to 1.0\r\nLOGOUT would inject a LOGOUT command after the ID command.
4. Trigger the injection: Submit the crafted input through the application's interface that invokes ImapConnection::id(), causing the library to send a malformed IMAP command sequence to the mail server.
5. Execute arbitrary IMAP commands: The injected command (e.g., FETCH, STORE, EXPUNGE, LOGOUT) is processed by the IMAP server with the privileges of the authenticated session, enabling email exfiltration, deletion, or session termination (GitHub Advisory, GitHub Commit).

• Network: Unexpected or malformed IMAP ID command sequences in network traffic, particularly those containing CRLF sequences (\r\n) or unescaped quote characters within ID parameter values; unusual IMAP commands (e.g., LOGOUT, EXPUNGE, FETCH) immediately following an ID command in the same session.
• Logs: IMAP server logs showing multi-command sequences originating from a single ID command invocation; repeated or anomalous ID commands with non-standard parameter formatting from the same client IP.
• Application Logs: PHP application logs showing unexpected IMAP responses or errors from the id() function in ImapConnection.php; unusual patterns of email deletion or session termination events correlated with ID command calls.

Upgrade directorytree/imapengine to version 1.22.3 or later, which applies proper escaping via Str::escape() on all ID command parameters (GitHub Commit, GitHub Advisory). If immediate patching is not feasible, restrict IMAP service access to trusted networks and enforce strict input validation on any user-supplied data passed to the id() function at the application layer. Monitor IMAP server logs for anomalous command sequences as a compensating control.

The vulnerability was reported by security researcher Wan Amirul Hakim Wan Yuhainis, who published a proof-of-concept via GitHub Gist (Snyk). Red Hat tracked the advisory, and it was indexed by INCIBE-CERT and multiple vulnerability aggregators shortly after disclosure (Red Hat). No significant broader media coverage or notable community controversy has been identified beyond standard vulnerability database indexing.