CVE-2026-91100 in Linux Imaging and Printing Software
Summary
by MITRE • 09/16/2026
HP has identified and remediated multiple externally reported vulnerabilities within HPLIP. The findings affect several software components that could potentially enable remote code execution, privilege escalation, denial of service, information disclosure, or unauthorized file modification under certain conditions.
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Analysis
by VulDB Data Team • 09/16/2026
Hewlett-Packard has addressed a cluster of security flaws identified in the HP Linux Imaging and Printing (HPLIP) suite, resolving issues reported by external researchers that pose significant risks to system integrity and confidentiality. These vulnerabilities span multiple software components within the HPLIP ecosystem, creating attack surfaces that can be exploited under specific conditions to achieve severe outcomes including remote code execution, privilege escalation, denial of service, information disclosure, and unauthorized file modification. The remediation effort underscores the critical nature of these defects, which stem from insufficient input validation and improper handling of data structures within the printing subsystems that interact with both local users and network services.
The technical flaw underlying many of these vulnerabilities lies in the inadequate sanitization of user-supplied inputs passed to various HPLIP utilities and backend drivers. When maliciously crafted data is processed, it can lead to memory corruption or logic errors that allow an attacker to execute arbitrary commands on the target system. This aligns with CWE-94 Improper Control of Generation of Code (Code Injection) and CWE-120 Buffer Overflow, where insufficient bounds checking permits overwriting adjacent memory regions. In scenarios involving remote interaction, such as through networked printing protocols or web interfaces managed by HPLIP components, these flaws can be triggered without local authentication, facilitating Remote Code Execution classified under MITRE ATT&CK technique T1059 Command and Scripting Interpreter. The ability to execute code remotely transforms a simple printer management tool into a potent vector for initial access in enterprise environments where printing services are exposed or accessible via internal networks.
Beyond remote execution, the vulnerabilities also facilitate privilege escalation and unauthorized file modification. An attacker who has gained limited user-level access through other means can exploit these flaws to elevate privileges to those of the system administrator or root user. This is consistent with CWE-269 Improper Privilege Management, where the application fails to enforce proper separation between privileged operations and untrusted input. Furthermore, the potential for unauthorized file modification allows attackers to alter configuration files, scripts, or even binary executables associated with the printing service. Such actions can lead to persistent backdoors or system instability, falling under CWE-732 Incorrect Permission Assignment for Critical Resource. The combination of these capabilities means that a single vulnerability chain could allow an adversary to move from initial foothold to full control over the host machine, compromising both availability and confidentiality.
The operational impact of these vulnerabilities is substantial, particularly in environments where HPLIP is used extensively or configured with elevated permissions by default. Denial of Service conditions can be induced through malformed inputs that cause crashes or infinite loops within the processing threads, disrupting printing services for all users on the system. This aligns with CWE-400 Uncontrolled Resource Consumption and MITRE ATT&CK technique T1499 Endpoint Denial of Service. Information disclosure vulnerabilities may leak sensitive data such as network configurations, user credentials stored in configuration files, or internal state information that aids further exploitation efforts. These disclosures correspond to CWE-200 Exposure of Sensitive Information to an Unauthorized Actor and contribute to the overall risk profile by providing attackers with intelligence necessary for more sophisticated attacks.
Mitigation strategies must focus on both immediate patching and long-term architectural hardening. Organizations should immediately apply the latest updates provided by HP, ensuring that all HPLIP components are brought to a secure version state. It is critical to verify that automatic update mechanisms are enabled or manually checked regularly against vendor advisories. Beyond patching, system administrators should enforce principle of least privilege by running printing services under dedicated, low-privilege accounts rather than root or standard user accounts with broad permissions. Network segmentation plays a vital role in limiting exposure; HPLIP-related ports and interfaces should not be exposed to untrusted networks such as the public internet. Additionally, implementing strict input validation at application boundaries and monitoring system logs for anomalous behavior related to printing services can help detect exploitation attempts early. Regular audits of file permissions on critical directories used by HPLIP will also reduce the risk associated with unauthorized modification vulnerabilities.