CVE-2026-54581 in mport
Summary
by MITRE • 09/17/2026
mport is the MidnightBSD Package Manager. Prior to 2.7.8, the mport_fetch_bootstrap_index() function in libmport/fetch.c could return success when bootstrap index hash verification encountered a missing or invalid hash because the failure path did not preserve a fatal result. A network attacker or compromised mirror able to alter bootstrap index content or its transport path could therefore cause mport to proceed with an unverified or tampered bootstrap package index. This issue is fixed in version 2.7.8.
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Analysis
by VulDB Data Team • 09/17/2026
The MidnightBSD Package Manager, known as mport, serves as the primary tool for software installation and system maintenance on the MidnightBSD operating system. A critical security flaw was identified within the libmport library, specifically affecting the mport_fetch_bootstrap_index() function located in fetch.c. This vulnerability stems from an improper error handling mechanism during the verification of bootstrap index hashes. The bootstrap index is a fundamental component that lists available packages and their metadata, allowing the package manager to locate and retrieve software. When this file is fetched from remote mirrors or repositories, it must be cryptographically verified against a known hash to ensure integrity and authenticity. However, prior to version 2.7.8, if the verification process encountered a missing or invalid hash, the function failed to correctly propagate this failure status back to the calling context. Instead of returning an error code that would halt execution, it erroneously returned success.
This logic flaw creates a significant integrity violation where mport proceeds with operations using unverified data. In a typical secure workflow, any discrepancy in cryptographic verification should immediately abort the process and alert the user or administrator. Because the failure path did not preserve the fatal result, the package manager assumes the bootstrap index is valid even when it has been tampered with or corrupted during transit. This behavior effectively bypasses the integrity checks designed to protect against supply chain attacks and man-in-the-middle modifications. An attacker who can manipulate network traffic or compromise a trusted mirror server could inject malicious metadata into the bootstrap index without detection by mport itself.
The operational impact of this vulnerability is severe, as it undermines the trust model of the package management system. By accepting an unverified bootstrap index, mport may proceed to download and install packages based on manipulated manifests. This can lead to the installation of compromised software that contains malware, backdoors, or other malicious payloads disguised as legitimate updates. The attacker gains the ability to control which versions of packages are installed, potentially introducing vulnerabilities into the system under the guise of routine maintenance. Since package managers often run with elevated privileges to modify system files and configurations, successful exploitation could result in full system compromise, data exfiltration, or persistent access for an adversary.
This vulnerability aligns with CWE-253, which describes improper check for unusual or unexpected conditions, specifically where a function fails to handle error states correctly. It also relates to CWE-697, incorrect comparison, as the logic incorrectly interprets a failure state as success. From a tactical perspective, this flaw facilitates supply chain attacks and aligns with MITRE ATT&CK techniques such as T1584.002, Compromise Software Supply Chain, where an adversary compromises software distribution channels to distribute malicious updates. It also touches upon T1609, Modify System Image, by allowing unauthorized modifications to the system's package database.
To mitigate this risk, organizations running MidnightBSD must upgrade mport to version 2.7.8 or later as soon as possible. This update corrects the error handling logic in libmport/fetch.c to ensure that any failure during hash verification results in a proper abort of the operation rather than silent continuation. Until the upgrade is applied, administrators should exercise extreme caution when fetching package indices from untrusted sources and consider implementing additional network-level integrity checks or using only verified mirrors with known good hashes stored locally. Regular auditing of installed packages against official checksums can also help detect any potential compromise resulting from prior exposure to this vulnerability.