CVE-2025-26506 Overview
CVE-2025-26506 affects multiple HP LaserJet Pro, HP LaserJet Enterprise, and HP LaserJet Managed printer models. The flaw allows remote code execution and elevation of privilege when the printer processes a malicious PostScript print job. The weakness is classified as a stack-based buffer overflow [CWE-121] in the PostScript interpreter exposed by the printing service.
The vulnerability is network-reachable and requires no authentication or user interaction, making any printer reachable from an untrusted network a viable target.
Critical Impact
A crafted PostScript print job can execute arbitrary code on the printer's firmware with elevated privileges, providing attackers a persistent foothold inside corporate networks via embedded devices.
Affected Products
- HP LaserJet Pro printer models (multiple SKUs including 499q9e, 4ra80a, 5hh48a series firmware)
- HP LaserJet Enterprise printer models (multiple SKUs including 74p25a, 74t92a, 759v0e series firmware)
- HP LaserJet Managed printer models (multiple SKUs including 8d7l0a, 8d7l1a, 8d7l2a series firmware)
Discovery Timeline
- 2025-02-14 - CVE-2025-26506 published to NVD
- 2026-01-15 - Last updated in NVD database
Technical Details for CVE-2025-26506
Vulnerability Analysis
The vulnerability resides in the PostScript interpreter embedded in affected HP LaserJet firmware. PostScript is a Turing-complete page description language, and the interpreter must parse complex operators, strings, and procedure definitions submitted as print jobs. A stack-based buffer overflow [CWE-121] occurs when the interpreter processes specific PostScript constructs without enforcing correct boundary checks on input length.
Because the printing service listens on the network (typically TCP/9100 raw print, IPP, or LPD), an unauthenticated remote attacker can submit the malicious job directly. Successful exploitation grants code execution at the privilege level of the print processing component, enabling elevation of privilege within the device firmware.
Printers operate as long-lived network appliances and rarely receive endpoint security monitoring. Compromise can therefore yield persistent access, credential harvesting from saved scan-to-folder or LDAP configurations, and lateral pivoting into internal subnets.
Root Cause
The root cause is improper validation of input boundaries inside the PostScript parser. When attacker-controlled data exceeds the size of a fixed-size stack buffer in the interpreter, adjacent stack memory including the saved return address is overwritten, allowing redirection of execution flow.
Attack Vector
The attack vector is the network print service. An attacker submits a malicious PostScript print job to the printer over a standard print protocol. No user interaction or credentials are required, although the CVSS vector indicates attack complexity is high, implying a non-trivial exploit primitive must be built against the specific firmware target.
The vulnerability manifests in the PostScript parsing path of the affected firmware. No verified public proof-of-concept code is currently available; refer to the HP Security Bulletin for vendor-supplied technical details.
Detection Methods for CVE-2025-26506
Indicators of Compromise
- Unexpected outbound network connections originating from printer IP addresses, particularly to external hosts or unusual internal subnets.
- Printer firmware version strings that do not match the patched builds listed in the HP security bulletin.
- Anomalous print job payloads containing unusually long PostScript strings, deeply nested procedures, or non-printable binary sequences submitted to TCP/9100, IPP (TCP/631), or LPD (TCP/515).
Detection Strategies
- Inventory all HP LaserJet devices and compare installed firmware revisions against the fixed versions published in the HP advisory.
- Inspect print server logs and network flow data for jobs delivered directly to printer IP addresses, bypassing the centralized print server.
- Apply intrusion detection signatures on print protocol ports that flag malformed or oversized PostScript operators.
Monitoring Recommendations
- Aggregate printer syslog and SNMP traps into a centralized logging platform and alert on firmware changes, reboots, and configuration modifications.
- Monitor egress traffic from printer VLANs and alert on any traffic that is not destined for known management endpoints.
- Track authentication failures and configuration access attempts against printer embedded web servers.
How to Mitigate CVE-2025-26506
Immediate Actions Required
- Apply the firmware updates published by HP for each affected LaserJet model as documented in the vendor advisory.
- Restrict access to printer raw print (TCP/9100), IPP, and LPD ports so that only authorized print servers can reach the devices.
- Disable PostScript processing on printers that only require PCL or PDF workflows, where the firmware permits this configuration.
Patch Information
HP has released firmware updates addressing this vulnerability. Refer to the HP Security Bulletin HPSBPI04007 for the list of affected product numbers and the corresponding fixed firmware revisions. Update each device through the HP Web Jetadmin console, the embedded web server, or the centralized fleet management tool used in your environment.
Workarounds
- Place printers on a dedicated, segmented VLAN with strict ingress and egress access control lists to limit exposure if patching cannot be performed immediately.
- Require print jobs to be submitted through a hardened print server rather than directly to the printer, and block direct TCP/9100 access from user subnets.
- Disable unused network protocols and services on the printer embedded web server, including FTP, Telnet, and legacy SNMP communities.
# Example firewall rules restricting printer access to a designated print server
# Replace 10.0.10.5 with your print server IP and 10.0.50.0/24 with your printer subnet
iptables -A FORWARD -s 10.0.10.5 -d 10.0.50.0/24 -p tcp --dport 9100 -j ACCEPT
iptables -A FORWARD -s 10.0.10.5 -d 10.0.50.0/24 -p tcp --dport 631 -j ACCEPT
iptables -A FORWARD -s 10.0.10.5 -d 10.0.50.0/24 -p tcp --dport 515 -j ACCEPT
iptables -A FORWARD -d 10.0.50.0/24 -p tcp --dport 9100 -j DROP
iptables -A FORWARD -d 10.0.50.0/24 -p tcp --dport 631 -j DROP
iptables -A FORWARD -d 10.0.50.0/24 -p tcp --dport 515 -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
