CVE-2026-91101 Overview
CVE-2026-91101 documents multiple externally reported vulnerabilities in HP Linux Imaging and Printing (HPLIP). HP states the flaws affect several software components and could enable remote code execution, privilege escalation, denial of service, information disclosure, or unauthorized file modification under specific conditions. The vulnerability is classified under [CWE-129] (Improper Validation of Array Index). The attack vector is physical, meaning an adversary needs local physical access to the affected system to trigger the flaw. HP has released remediations through security bulletin HPSBPI04151.
Critical Impact
Successful exploitation can result in high impact to system availability through denial of service on affected HPLIP components.
Affected Products
- HP Linux Imaging and Printing (HPLIP) software components
- HP printing and imaging devices relying on HPLIP drivers
- Linux systems with HPLIP installed for HP device support
Discovery Timeline
- 2026-09-16 - CVE-2026-91101 published to NVD
- 2026-09-17 - Last updated in NVD database
Technical Details for CVE-2026-91101
Vulnerability Analysis
CVE-2026-91101 aggregates multiple flaws within HPLIP, HP's open-source driver package for Linux-based printing and scanning. According to HP's bulletin, the issues span several components and, depending on the specific weakness, may lead to remote code execution, privilege escalation, denial of service, information disclosure, or unauthorized file modification.
The classification under [CWE-129] indicates that at least one component fails to properly validate array indices before using them in memory operations. Improper index validation can cause out-of-bounds reads or writes, corrupting adjacent memory or crashing the process.
The attack vector is physical, meaning the adversary must have direct hardware access to the target system or peripheral to trigger the flaw. The primary observable impact is on availability, consistent with a denial-of-service outcome on the HPLIP process.
Root Cause
The root cause centers on improper validation of an array index within HPLIP components. When input driving the index calculation is untrusted or malformed, the code reads or writes memory outside intended bounds. This memory safety violation destabilizes the process and can, in adjacent conditions, lead to code execution or information disclosure.
Attack Vector
An attacker with physical access to the system or an attached HP imaging device can supply crafted input that triggers the vulnerable code path in HPLIP. Because the vector is physical rather than network or local user context, exploitation requires proximity to the printer, scanner, or host running the HPLIP stack. Refer to the HP Security Bulletin HPSBPI04151 for component-level technical detail.
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Stop Exploit AttemptsDetection Methods for CVE-2026-91101
Indicators of Compromise
- Unexpected crashes or restarts of HPLIP daemons such as hpd, hp-systray, or related CUPS backend processes.
- Segmentation faults referencing HPLIP binaries in /var/log/syslog, journalctl, or dmesg output.
- Unauthorized modification of files under HPLIP configuration or spool directories.
Detection Strategies
- Monitor for abnormal termination of HPLIP processes and correlate with recent physical device interactions.
- Track file integrity on HPLIP installation paths and CUPS configuration directories to identify unauthorized modification.
- Review CUPS and HPLIP logs for parser errors, malformed device responses, or repeated command failures indicating exploitation attempts.
Monitoring Recommendations
- Enable auditd rules on /etc/hp, /var/log/hp, and CUPS spool paths to record file modification events.
- Ingest syslog and journal telemetry into a centralized SIEM to correlate crash signatures across the fleet.
- Alert on new or unexpected USB device connections to hosts running HPLIP, especially on servers and multi-user workstations.
How to Mitigate CVE-2026-91101
Immediate Actions Required
- Apply the updated HPLIP packages referenced in HP Security Bulletin HPSBPI04151 as soon as they are available for your distribution.
- Inventory all Linux hosts running HPLIP and prioritize patching for systems with physical exposure or shared access.
- Restrict physical and USB access to systems running HPLIP where feasible.
Patch Information
HP has remediated the reported vulnerabilities and published fixed component versions in security bulletin HPSBPI04151. Consult the bulletin for exact fixed versions per affected component and validate that your distribution's HPLIP package matches or exceeds those versions.
Workarounds
- Disable or remove HPLIP on Linux systems that do not require HP printing or scanning support.
- Limit which user accounts can attach or interact with HP imaging devices through udev rules and group membership.
- Segment print servers from general workstation networks to reduce lateral impact if an HPLIP process is compromised.
# Verify installed HPLIP version and compare against the fixed version in HPSBPI04151
hp-check -r | grep -i "HPLIP version"
dpkg -l | grep -i hplip # Debian/Ubuntu
rpm -qa | grep -i hplip # RHEL/Fedora/SUSE
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
