Description

An attacker that has valid credentials can send an invalid IMAP URLFETCH command, which causes uninitialized memory to be included in the error response returned to the client. Process memory contents can be disclosed to the client, which may include sensitive data. Disable the IMAP URLAUTH functionality. Update to non-vulnerable version. No publicly available exploits are known.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "4.3",
  "pubDate": "2026-08-28T12:16:29.640Z",
  "pubdate": "2026-08-28T12:16:29.640Z",
  "executiveSummary": "This vulnerability is an information disclosure flaw residing in the IMAP URLFETCH command implementation. It allows an authenticated user to trigger an error response that includes contents of uninitialized process memory. By leveraging this defect, an attacker can exfiltrate sensitive data residing in the server's memory space, potentially including session tokens, credentials, or other confidential information processed by the application. The vulnerability is categorized as an improper memory initialization issue. Successful exploitation requires the attacker to possess valid credentials, limiting the attack surface to authenticated users. The impact is significant as it facilitates unauthorized data access and potential reconnaissance for further exploitation. There are no publicly known exploits for this vulnerability at this time. Remediation requires updating to the patched version of the software or disabling the vulnerable IMAP URLAUTH functionality to eliminate the attack vector.",
  "technicalDetails": "The vulnerability exists within the IMAP server implementation, specifically involving the handling of the URLFETCH command. The root cause is a failure to properly sanitize or clear memory buffers before they are included in an error response returned to the IMAP client. When an invalid URLFETCH command is processed by the server, the application logic generates an error condition. During the construction of this error response, the system improperly references an uninitialized memory region that happens to contain residual data from previous process operations.\nThe attack flow begins with an authenticated attacker establishing an IMAP session. Upon successful authentication, the attacker submits a malformed or invalid URLFETCH request designed to trigger the specific error handling path where the memory disclosure occurs. Because the server fails to zero out or reinitialize the memory buffer designated for the error response payload, the buffer retains stale data from the process heap or stack. The server then transmits this sensitive, leaked memory data directly back to the attacker’s client as part of the IMAP protocol communication.\nThis vulnerability is primarily a server-side memory handling error. The affected component is the IMAP subsystem responsible for processing URLFETCH commands. Exploitation does not require elevated administrative privileges, only valid user credentials within the IMAP environment. The scope of the disclosure is limited to the memory contents currently accessible to the IMAP process. This could include sensitive information from other user sessions, internal configuration data, or raw pointers that might aid in further memory corruption attacks. Given that the IMAP process often handles authentication credentials and mail content, the potential for leakage of highly sensitive data is high. The exploitability is restricted by the need for a specific, invalid command structure that triggers the vulnerable error path without crashing the process, which would result in a Denial of Service rather than an information disclosure."
}