CVE-2025-26506: HP LaserJet Printers RCE Vulnerability

CVE-2025-26506 Overview

CVE-2025-26506 is a critical stack-based buffer overflow vulnerability affecting HP LaserJet Pro, HP LaserJet Enterprise, and HP LaserJet Managed Printers. The vulnerability occurs during the processing of specially crafted PostScript print jobs, potentially allowing remote attackers to execute arbitrary code and escalate privileges on vulnerable devices.

Critical Impact

This vulnerability enables unauthenticated remote code execution and privilege escalation on affected HP printers through malicious PostScript print jobs, potentially allowing complete compromise of printing infrastructure.

Affected Products

• HP LaserJet Pro Printers
• HP LaserJet Enterprise Printers
• HP LaserJet Managed Printers

Discovery Timeline

• 2025-02-14 - CVE CVE-2025-26506 published to NVD
• 2025-02-14 - Last updated in NVD database

Technical Details for CVE-2025-26506

Vulnerability Analysis

This vulnerability is classified as CWE-121 (Stack-based Buffer Overflow), a memory corruption issue that occurs when a program writes beyond the boundary of a fixed-size buffer on the stack. In the context of HP LaserJet printers, this vulnerability is triggered when the device's PostScript interpreter processes a maliciously crafted print job.

PostScript is a page description language commonly used in professional printing environments. The HP printer firmware fails to properly validate the size and content of certain PostScript operations, allowing an attacker to overflow a stack buffer with attacker-controlled data. This overflow can overwrite critical stack values including return addresses and function pointers, enabling code execution.

The network-accessible nature of this vulnerability means that any user or system capable of sending print jobs to an affected device could potentially exploit it, though the attack does require some level of complexity to successfully execute. Successful exploitation results in complete device compromise with the highest level of privileges available on the printer firmware.

Root Cause

The root cause of CVE-2025-26506 is improper bounds checking in the PostScript print job processing functionality of affected HP LaserJet firmware. When handling specific PostScript operations or data structures, the firmware allocates a fixed-size buffer on the stack but does not adequately verify that incoming data fits within the allocated space. This allows oversized or malformed input to exceed buffer boundaries and corrupt adjacent stack memory.

Attack Vector

The attack vector for this vulnerability is network-based. An attacker with network access to a vulnerable HP LaserJet printer can submit a specially crafted PostScript print job to the device. The malicious print job contains carefully constructed PostScript code designed to trigger the buffer overflow during parsing or interpretation. When processed by the vulnerable firmware, the overflow corrupts stack memory in a controlled manner, allowing the attacker to redirect code execution to their payload.

The vulnerability can be exploited remotely without authentication, though the attack requires precise crafting of the malicious PostScript content to achieve reliable code execution. For technical details on the vulnerability, refer to the HP Security Bulletin.

Detection Methods for CVE-2025-26506

Indicators of Compromise

• Unusual print jobs containing abnormally large PostScript data or non-standard PostScript commands
• Unexpected printer behavior including reboots, configuration changes, or network connections
• Anomalous outbound network traffic from printer devices to unknown destinations
• Printer log entries showing parsing errors or crashes during print job processing

Detection Strategies

• Implement network monitoring to analyze print traffic for malformed or unusually large PostScript payloads
• Enable comprehensive logging on HP printers and forward logs to SIEM for analysis
• Deploy network segmentation rules that restrict direct internet access from printer devices
• Use SentinelOne Singularity for network visibility to detect anomalous printer behavior and lateral movement attempts

Monitoring Recommendations

• Monitor print queues for jobs with suspicious characteristics or from unexpected sources
• Establish baseline network behavior for printers and alert on deviations
• Review printer firmware versions regularly against HP security advisories
• Implement network-level controls to log and inspect traffic to printing devices

How to Mitigate CVE-2025-26506

Immediate Actions Required

• Apply firmware updates from HP immediately to all affected LaserJet Pro, Enterprise, and Managed Printers
• Restrict network access to printers using firewall rules or VLAN segmentation
• Disable unnecessary PostScript processing if not required for business operations
• Audit print job sources and implement print server access controls

Patch Information

HP has released a security bulletin addressing this vulnerability. Administrators should consult the HP Security Bulletin HPSBPI04007 to identify updated firmware versions for their specific printer models and apply patches as directed. Firmware updates can typically be applied through the HP Web Jetadmin tool, the printer's embedded web server, or USB installation methods.

Workarounds

• Disable PostScript processing on affected printers and use PCL or other printer languages where possible
• Implement strict network segmentation to isolate printers from untrusted network segments
• Configure firewalls to limit print traffic to authorized print servers only
• Enable IP address filtering on printer devices to restrict access to trusted hosts

# Example network segmentation configuration for printer isolation
# Restrict printer VLAN access from workstations - sample iptables rules
iptables -A FORWARD -s 10.0.1.0/24 -d 10.0.50.0/24 -p tcp --dport 9100 -j DROP
iptables -A FORWARD -s 10.0.100.10 -d 10.0.50.0/24 -p tcp --dport 9100 -j ACCEPT
# Only allow print server (10.0.100.10) to communicate with printer VLAN (10.0.50.0/24)