CVE-2026-17639: HP Smart Tank Printer DoS Vulnerability

CVE-2026-17639 Overview

CVE-2026-17639 affects certain HP Smart Tank All-in-One printers. An unauthenticated attacker can trigger a denial of service (DoS) condition by sending multiple concurrent HTTP requests to the device. The printer becomes unavailable until the resource exhaustion clears or the device is restarted. The flaw maps to CWE-400 (Uncontrolled Resource Consumption). No authentication, user interaction, or elevated privileges are required. The attack requires only network reachability to the printer's embedded web server.

Critical Impact
An unauthenticated network attacker can render affected HP Smart Tank printers unavailable by flooding the embedded HTTP service with concurrent requests.

Affected Products

HP Smart Tank All-in-One printer series (specific models listed in the HP Security Bulletin)
Devices exposing the embedded HTTP management interface on the network
Firmware versions prior to the HP-published fix

Discovery Timeline

2026-08-17 - CVE-2026-17639 published to the National Vulnerability Database
2026-08-17 - Last updated in NVD database
Vendor advisory: HP Security Bulletin

Technical Details for CVE-2026-17639

Vulnerability Analysis

The vulnerability is a network-reachable denial of service condition in the embedded HTTP service of affected HP Smart Tank All-in-One printers. When the device receives multiple concurrent HTTP requests, it exhausts internal resources handling connection state, memory, or worker threads. Once resources are consumed, the printer stops responding to legitimate requests for printing, scanning, or management. The vulnerability affects availability only. There is no impact to confidentiality or integrity of data on the device according to the published metrics. Refer to the HP Security Bulletin for the definitive list of affected models and firmware.

Root Cause

The root cause is uncontrolled resource consumption [CWE-400] in the embedded web server. The firmware does not enforce sufficient limits on concurrent client connections or request processing. When many HTTP requests arrive simultaneously, the printer's constrained embedded resources are depleted. This causes the HTTP service, and potentially the broader device, to become unresponsive.

Attack Vector

The attack vector is network. An adversary with TCP reachability to the printer's HTTP port opens numerous concurrent connections and issues HTTP requests. No credentials are needed. The requests do not require malformed payloads. Volume alone drives the device into an unavailable state. Printers exposed to untrusted network segments, guest networks, or the internet are the primary risk profile. The vulnerability does not permit code execution or data disclosure. See the vendor bulletin for details on the fixed firmware.

Detection Methods for CVE-2026-17639

Indicators of Compromise

Spikes in concurrent TCP connections to printer IP addresses on HTTP (port 80) or HTTPS (port 443).
Printer web interface, IPP, or print spooler becoming unreachable while ICMP may still respond.
Repeated failed print or scan jobs and user reports of unresponsive multifunction devices.
Network flow logs showing a single source generating high request rates against printer subnets.

Detection Strategies

Baseline normal HTTP traffic volume to printer subnets and alert on deviations.
Correlate printer unavailability events with concurrent connection surges from a single source.
Monitor SNMP sysUpTime resets on printers, which can indicate forced restarts after DoS.
Inspect firewall and NetFlow data for scanning behavior targeting printer management ports.

Monitoring Recommendations

Ingest network telemetry, printer syslog, and SNMP traps into a centralized analytics platform for correlation.
Configure alerts when printer HTTP endpoints exceed a defined concurrent connection threshold.
Track printer availability with synthetic health checks against the management interface.
Review logs of any reverse proxy or NAC device fronting the printer VLAN for anomalous request patterns.

How to Mitigate CVE-2026-17639

Immediate Actions Required

Apply the firmware update referenced in the HP Security Bulletin as soon as HP publishes the fixed version for your model.
Remove any direct internet exposure of printer management interfaces and confirm devices are not reachable from untrusted networks.
Place printers on a dedicated management VLAN with strict ACLs limiting HTTP/HTTPS access to authorized print servers and administrators.
Inventory HP Smart Tank All-in-One devices, record firmware versions, and prioritize patching for internet-exposed or high-value units.

Patch Information

HP has published guidance for affected HP Smart Tank All-in-One printers in the HP Security Bulletin. Administrators should consult the bulletin to identify affected models and the corresponding fixed firmware version, then update devices through HP Smart, the Embedded Web Server, or HP's firmware update tools.

Workarounds

Restrict inbound access to the printer's HTTP and HTTPS ports using network segmentation or host-based ACLs on upstream switches.
Disable the Embedded Web Server on printers where remote management is not required, following HP's documented procedure.
Rate-limit connections to printer management interfaces at the firewall or reverse proxy layer to reduce concurrent request exposure.
Monitor printer availability and automatically alert operations teams so devices can be power-cycled if a DoS condition is observed.

bash

# Configuration example: restrict printer HTTP/HTTPS to management subnet
# (adjust interface, addresses, and syntax for your firewall platform)

# Allow only the admin subnet to reach the printer management interface
iptables -A FORWARD -s 10.10.20.0/24 -d 10.20.30.40 -p tcp -m multiport --dports 80,443 -j ACCEPT
iptables -A FORWARD -d 10.20.30.40 -p tcp -m multiport --dports 80,443 -j DROP

# Optional: rate-limit new HTTP connections to the printer
iptables -A FORWARD -d 10.20.30.40 -p tcp --dport 80 \
  -m conntrack --ctstate NEW -m limit --limit 20/minute --limit-burst 40 -j ACCEPT