CVE-2025-3079 Overview
CVE-2025-3079 is a passback vulnerability affecting Canon production printers, office and small office multifunction printers, and laser printers. The flaw, categorized under [CWE-522] Insufficiently Protected Credentials, allows an authenticated attacker with administrative privileges to reconfigure the device to send stored authentication credentials to an attacker-controlled server. Canon disclosed the issue through PSIRT advisory CP2025-004. The vulnerability operates over the network and can expose credentials used for LDAP, SMB, FTP, Kerberos, or other integrated authentication services.
Critical Impact
An authenticated administrator can redirect printer-stored credentials to a malicious endpoint, exposing enterprise directory and file-sharing credentials that may enable lateral movement across the network.
Affected Products
- Canon production printers (per advisory CP2025-004)
- Canon office and small office multifunction printers
- Canon laser printers
Discovery Timeline
- 2025-05-20 - CVE-2025-3079 published to NVD
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2025-3079
Vulnerability Analysis
The vulnerability is a credential passback issue in Canon multifunction and laser printer firmware. Affected devices store authentication credentials for backend services such as LDAP, SMB shares, FTP servers, and email relays. The device permits an administrator to modify the server address associated with these stored credentials without re-authenticating to that backend. When the device next attempts authentication, it sends the previously stored credentials to the newly configured server. This behavior allows the credentials to be exfiltrated in cleartext or in a captureable form to an attacker-controlled host. The flaw maps to [CWE-522] Insufficiently Protected Credentials and is network-reachable through the printer's administrative web interface or remote management protocols.
Root Cause
The device firmware separates the storage of credentials from the destination server configuration. Modifying the destination does not invalidate or re-prompt for the associated secret. This design omits any binding between credential and intended endpoint, enabling reuse against arbitrary hosts.
Attack Vector
An attacker requires high-privilege administrative access to the printer's management interface. After authenticating, the attacker changes the configured LDAP, SMB, or SMTP server hostname or IP to a system they control. The printer then transmits the stored credentials to that destination during normal authentication flows or scheduled operations. Default or weak administrator passwords on internet-exposed printers materially increase exploitability.
No verified proof-of-concept code is publicly available. Refer to the Canon PSIRT Advisory CP2025-004 for vendor technical details.
Detection Methods for CVE-2025-3079
Indicators of Compromise
- Unexpected changes to LDAP, SMB, FTP, or SMTP server addresses in printer configuration logs.
- Outbound authentication attempts from printer IP addresses to non-corporate or external destinations.
- Administrative logins to printer web interfaces from unusual source addresses or outside business hours.
- Directory service authentication failures originating from spoofed or unauthorized hosts using printer service accounts.
Detection Strategies
- Audit printer configuration files and management logs for modifications to authentication endpoint settings.
- Monitor network egress from printer VLANs for connections to untrusted IP ranges or external hosts.
- Correlate Active Directory authentication logs against the known printer service accounts to identify anomalous source hosts.
Monitoring Recommendations
- Enable and centralize syslog forwarding from Canon devices to a SIEM for configuration-change visibility.
- Alert on any administrative session to printer management interfaces from non-administrative subnets.
- Track the integrity of stored server addresses on printers using periodic configuration baselining.
How to Mitigate CVE-2025-3079
Immediate Actions Required
- Apply firmware updates listed in Canon PSIRT Advisory CP2025-004 for affected printer models.
- Change all administrator passwords on Canon printers and rotate any credentials previously stored on the devices (LDAP, SMB, FTP, SMTP).
- Remove printer management interfaces from internet exposure and restrict access to a dedicated administrative network segment.
- Review printer configuration for unauthorized changes to authentication server addresses.
Patch Information
Canon has published mitigation and remediation guidance through PSIRT advisory CP2025-004. Refer to the Canon CP2025-004 Mitigation Guide and the Canon Hardening Guidelines for model-specific firmware versions and configuration steps. Regional resources are available from the Canon Europe Product Security and Canon Japan Vulnerability Response pages.
Workarounds
- Enforce strong, unique administrator passwords on all Canon printers and disable any default accounts.
- Place printers on an isolated VLAN with egress filtering that restricts outbound traffic to known internal authentication and file servers only.
- Use dedicated, least-privilege service accounts for printer integrations with directory services to limit blast radius if credentials are exposed.
- Disable unused authentication backends (LDAP, SMB, FTP) on devices that do not require them.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
