CVE-2026-4682 Overview
A stack-based buffer overflow vulnerability exists in certain HP DeskJet All-in-One multifunction printer (MFP) devices. The vulnerability is triggered when specially crafted Web Services for Devices (WSD) scan requests are improperly validated and handled by the MFP firmware. WSD Scan is a Microsoft Windows-based network scanning protocol that enables PCs to discover scanners and MFPs on a network and send scan jobs without requiring vendor-specific drivers or utilities.
An unauthenticated attacker with adjacent network access can exploit this vulnerability to execute arbitrary code on vulnerable HP DeskJet devices, potentially compromising the device completely and using it as a pivot point for further network attacks.
Critical Impact
Remote code execution on vulnerable HP multifunction printers allows attackers to take complete control of the device from the adjacent network without authentication.
Affected Products
- HP DeskJet All-in-One devices with WSD Scan functionality enabled
- Certain HP MFP devices with vulnerable firmware versions
- Network-connected HP printers exposing WSD services
Discovery Timeline
- 2026-04-15 - CVE-2026-4682 published to NVD
- 2026-04-15 - Last updated in NVD database
Technical Details for CVE-2026-4682
Vulnerability Analysis
This vulnerability is classified as CWE-121: Stack-based Buffer Overflow. The flaw resides in the firmware component responsible for parsing and handling incoming WSD scan requests. When a malformed WSD request containing an oversized payload is received, the MFP firmware fails to properly validate input boundaries before copying data to a stack-allocated buffer, resulting in memory corruption.
The attack requires adjacent network access, meaning the attacker must be on the same local network segment as the vulnerable printer. No user interaction or authentication is required to trigger the vulnerability, making it particularly dangerous in enterprise and home network environments where printers are commonly deployed.
Successful exploitation grants the attacker high-impact capabilities across confidentiality, integrity, and availability—allowing them to execute arbitrary code with the privileges of the firmware process, potentially exfiltrate scanned documents, modify device configuration, or render the device inoperable.
Root Cause
The root cause is improper input validation in the WSD protocol handler within the HP DeskJet firmware. The vulnerable code path fails to check the length of incoming data against the allocated buffer size before performing a memory copy operation, allowing an attacker to overflow the stack buffer with attacker-controlled data.
Stack-based buffer overflows in embedded systems like printers are particularly dangerous because these devices often lack modern exploit mitigations such as ASLR, DEP, or stack canaries that are standard on desktop and server operating systems.
Attack Vector
The attack is executed from the adjacent network (local network segment) by sending maliciously crafted WSD scan requests to the vulnerable printer. The attacker identifies vulnerable HP DeskJet devices on the network by scanning for WSD services, then transmits specially crafted WSD packets containing oversized or malformed scan request parameters.
When the vulnerable firmware processes these malicious requests, the buffer overflow overwrites critical stack data including return addresses. By carefully crafting the overflow payload, an attacker can redirect execution flow to arbitrary code, achieving remote code execution on the embedded device.
Detection Methods for CVE-2026-4682
Indicators of Compromise
- Unusual WSD traffic patterns or abnormally large WSD scan request packets on the network
- Unexpected printer behavior such as reboots, configuration changes, or unresponsive states
- Network connections originating from printer devices to unexpected external IP addresses
- Anomalous processes or services running on the MFP if device inspection capabilities exist
Detection Strategies
- Monitor network traffic for WSD protocol (typically UDP port 3702 and HTTP port 5357) anomalies
- Implement network segmentation to isolate printer traffic and enable focused monitoring
- Deploy intrusion detection signatures for malformed WSD requests or buffer overflow patterns
- Use SentinelOne Singularity platform to monitor for lateral movement attempts from compromised IoT devices
Monitoring Recommendations
- Enable logging on network firewalls and switches to capture printer-related traffic patterns
- Establish baseline network behavior for MFP devices to identify deviations
- Periodically audit printer firmware versions against HP security advisories
- Monitor for reconnaissance activities targeting printer services on the network
How to Mitigate CVE-2026-4682
Immediate Actions Required
- Check the HP Support Document for affected models and updated firmware
- Isolate vulnerable HP DeskJet devices on a separate network segment until patching is complete
- Disable WSD Scan functionality if not required for business operations
- Apply network access controls to restrict which hosts can communicate with printers
Patch Information
HP has released security guidance for this vulnerability. Administrators should consult the official HP Support Document to identify affected device models and download the appropriate firmware updates. It is critical to apply firmware updates as soon as they become available to remediate this high-severity vulnerability.
Workarounds
- Disable WSD Scan protocol on affected devices through the printer administration panel
- Implement firewall rules blocking WSD traffic (UDP 3702, TCP/HTTP 5357) to the printer
- Use network segmentation to place printers on isolated VLANs with restricted access
- Configure access control lists to limit printer management access to authorized administrator workstations only
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
