CVE-2026-91106 Overview
CVE-2026-91106 is a critical vulnerability affecting the HP Linux Imaging and Printing (HPLIP) software suite. HP has confirmed multiple externally reported flaws within HPLIP components that attackers can chain to achieve remote code execution, privilege escalation, denial of service, information disclosure, or unauthorized file modification. The root weakness is classified as a heap-based buffer overflow [CWE-122]. The vulnerability is exploitable over the network without authentication or user interaction, according to the published CVSS 4.0 vector.
Critical Impact
Remote, unauthenticated attackers can trigger a heap-based buffer overflow in HPLIP to execute arbitrary code, modify files, disclose sensitive data, or crash affected systems.
Affected Products
- HP Linux Imaging and Printing (HPLIP) software suite
- Linux hosts running HPLIP for HP printer and multifunction device support
- Downstream Linux distributions bundling vulnerable HPLIP packages
Discovery Timeline
- 2026-09-16 - CVE-2026-91106 published to the National Vulnerability Database
- 2026-09-17 - Last updated in NVD database
Technical Details for CVE-2026-91106
Vulnerability Analysis
HPLIP provides drivers, scanning, and management utilities for HP printers on Linux. HP's advisory identifies multiple vulnerabilities across HPLIP components that share a common outcome: attacker-controlled input reaches memory-handling routines that fail to enforce buffer boundaries. The Common Weakness Enumeration category CWE-122 (Heap-Based Buffer Overflow) describes the primary flaw class. Successful exploitation can corrupt heap metadata and adjacent objects, allowing an attacker to redirect execution flow. HP's bulletin further notes possible privilege escalation, denial of service, information disclosure, and unauthorized file modification depending on the specific component reached.
Root Cause
The vulnerability originates from insufficient bounds checking when HPLIP components parse externally supplied data into heap-allocated buffers. When attacker-controlled input exceeds the assumed buffer size, adjacent heap memory is overwritten. On Linux systems where HPLIP daemons or helper processes run with elevated permissions, the corruption can be leveraged for code execution in a privileged context.
Attack Vector
The CVSS 4.0 vector AV:N/AC:L/AT:N/PR:N/UI:N indicates that the attack path is reachable over the network, requires no privileges, and needs no user interaction. An attacker capable of reaching HPLIP-exposed services or driver-processing paths can send crafted input to trigger the heap overflow. Because HPLIP interacts with print jobs, device discovery, and management interfaces, hostile input may be delivered through print protocols or network-facing helper processes. HP has not confirmed public exploitation, and no proof-of-concept has been released at the time of publication.
// No verified proof-of-concept code is available.
// Refer to the HP Security Bulletin for component-level technical details.
Stop Remote Code Execution Before It Runs
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Stop Exploit AttemptsDetection Methods for CVE-2026-91106
Indicators of Compromise
- Unexpected crashes or restarts of HPLIP daemons such as hpssd, hp-systray, or CUPS backend hp processes.
- Segmentation faults referencing HPLIP shared libraries in /var/log/syslog, /var/log/messages, or journalctl output.
- Outbound network connections initiated by HPLIP processes to unfamiliar destinations.
- New or modified files owned by the lp user in unusual paths outside of /var/spool/cups/.
Detection Strategies
- Monitor process trees for child processes spawned by HPLIP binaries such as hp-* utilities, which should not normally launch shells or interpreters.
- Enable core dump collection on print servers to capture evidence of memory corruption for offline analysis.
- Correlate CUPS access logs with HPLIP process activity to identify malformed jobs that precede a crash.
Monitoring Recommendations
- Alert on privilege transitions where the lp service account executes commands outside its expected binary set.
- Track version inventory of the hplip package across Linux fleets and flag hosts running versions prior to the HP fix.
- Ingest syslog and audit records into a central data lake to enable retroactive hunting once vendor-specific indicators are published.
How to Mitigate CVE-2026-91106
Immediate Actions Required
- Apply the HPLIP updates referenced in the HP Security Bulletin as soon as vendor packages are available for your distribution.
- Restrict network access to hosts running HPLIP so that only trusted print clients can reach CUPS and HPLIP management ports.
- Audit installed HPLIP versions across all Linux endpoints and print servers, prioritizing internet-adjacent systems.
Patch Information
HP has released remediated versions of HPLIP as described in the HP Security Bulletin. Administrators should upgrade to the fixed HPLIP release through the vendor package or the distribution security channel, then restart CUPS and HPLIP-related services. Verify the running version with hp-check -r after upgrade.
Workarounds
- Disable HPLIP services on Linux hosts that do not require HP printer support using systemctl disable --now hplip.service.
- Block inbound access to CUPS ports (default TCP 631) at the host firewall on systems that do not need to accept remote print jobs.
- Remove the hplip package where HP devices are not in use to eliminate the vulnerable code path entirely.
# Verify installed HPLIP version and disable service if not required
hp-check -r | grep -i version
sudo systemctl disable --now hplip.service cups-browsed.service
sudo ufw deny 631/tcp
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
