CVE-2026-91104 Overview
CVE-2026-91104 affects the HP Linux Imaging and Printing (HPLIP) software suite. HP has identified and remediated multiple externally reported vulnerabilities within HPLIP components. The flaws could enable remote code execution, privilege escalation, denial of service, information disclosure, or unauthorized file modification under specific conditions. The vulnerability is categorized under [CWE-122] Heap-Based Buffer Overflow and is exploitable over the network without authentication or user interaction.
Critical Impact
Unauthenticated network attackers can trigger a heap-based buffer overflow in HPLIP components to execute arbitrary code, escalate privileges, or disclose sensitive information on affected systems.
Affected Products
- HP Linux Imaging and Printing (HPLIP) software suite
- HP printing and imaging components bundled with HPLIP
- Linux distributions shipping vulnerable HPLIP packages
Discovery Timeline
- 2026-09-16 - CVE-2026-91104 published to the National Vulnerability Database
- 2026-09-17 - Last updated in NVD database
Technical Details for CVE-2026-91104
Vulnerability Analysis
The vulnerability resides within HPLIP, HP's open-source driver stack for printing, scanning, and faxing on Linux systems. According to HP's security bulletin, multiple components contain flaws that map to a heap-based buffer overflow condition tracked under [CWE-122]. Successful exploitation can lead to arbitrary code execution in the context of the vulnerable HPLIP process.
Because HPLIP frequently runs with elevated permissions for device access and spool management, exploitation can result in privilege escalation on the host. Secondary impacts documented by HP include denial of service, information disclosure, and unauthorized file modification. The attack vector is network-based, meaning remote attackers can reach vulnerable endpoints without local access.
Root Cause
The root cause is improper bounds checking on heap-allocated buffers within HPLIP components. When a component processes attacker-controlled input, insufficient validation of size parameters permits writes beyond the intended allocation. This corrupts adjacent heap metadata or object pointers, which an attacker can steer toward controlled execution.
Attack Vector
An unauthenticated remote attacker delivers crafted input to a network-reachable HPLIP interface. No user interaction is required. The malformed payload triggers the heap overflow, allowing the attacker to overwrite memory structures and hijack control flow within the vulnerable process. HP has not published proof-of-concept exploitation code, and no public exploit is currently 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-2026-91104
Indicators of Compromise
- Unexpected hplip or hp-* process crashes, segmentation faults, or restarts logged in /var/log/syslog or journalctl.
- Anomalous outbound network connections initiated by HPLIP-related processes such as hpssd, hp-check, or CUPS filter binaries.
- New or modified files in HPLIP configuration directories or spool paths that do not correspond to administrative activity.
Detection Strategies
- Monitor process telemetry for HPLIP binaries spawning shells, interpreters, or network utilities such as bash, python, nc, or curl.
- Inspect network traffic to printing services and HPLIP daemons for oversized or malformed protocol messages that could indicate overflow attempts.
- Correlate crash events with subsequent privilege changes, cron modifications, or lateral movement from the affected host.
Monitoring Recommendations
- Enable auditd rules on Linux systems to track execve calls originating from HPLIP process trees.
- Forward syslog and CUPS logs to a centralized SIEM for retention and correlation with endpoint telemetry.
- Baseline normal HPLIP behavior per host and alert on deviations in child processes, file writes, and network destinations.
How to Mitigate CVE-2026-91104
Immediate Actions Required
- Apply the HPLIP updates published in the HP Security Bulletin to all affected Linux hosts.
- Inventory systems running HPLIP, including workstations, print servers, and multi-function device controllers, and prioritize internet-exposed assets.
- Restrict network access to HPLIP and CUPS listeners to trusted management segments until patches are deployed.
Patch Information
HP has released remediated HPLIP versions addressing the reported vulnerabilities. Administrators should consult the HP Security Bulletin for the specific fixed component versions and distribution-specific package updates. Linux distribution maintainers typically publish backported fixes through standard package repositories.
Workarounds
- Disable HPLIP services on hosts that do not require HP printing or scanning functionality.
- Block inbound access to HPLIP-related ports at the host firewall using iptables or nftables rules scoped to trusted subnets.
- Remove unused HPLIP components and drivers to reduce the attack surface until patches can be applied.
# Configuration example: identify and update HPLIP on Debian/Ubuntu systems
dpkg -l | grep -i hplip
sudo apt update && sudo apt install --only-upgrade hplip hplip-data
systemctl restart cups
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
