CVE-2026-54583 in mport
Summary
by MITRE • 09/17/2026
mport is the MidnightBSD Package Manager. Prior to 2.7.8, libmport/fetch.c did not consistently reject empty, dot, dot-dot, or slash-containing bundle filenames before composing package download and write paths. Malicious package index data could place an unsafe value in indexEntry->bundlefile, and the missing is_valid_bundle_filename() checks allowed downloaded package data to be written outside the intended cache location or to an unsafe destination name. 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 a critical infrastructure component for software distribution and system maintenance within the MidnightBSD operating environment. It relies on fetching package metadata from remote repositories to determine available updates or new installations. A significant security vulnerability was identified in versions prior to 2.7.8 regarding how the application handles bundle filenames during the download process. Specifically, the function responsible for validating input data failed to enforce strict constraints on special characters and path traversal sequences within the bundle filename field of package index entries. This oversight created a pathway for attackers to manipulate file system operations through maliciously crafted repository metadata.
The technical root cause lies in the fetch module, specifically within libmport/fetch.c. When processing package indices, the application constructs local file paths based on values provided by remote servers without sufficient validation. The missing implementation of an is_valid_bundle_filename check meant that inputs containing empty strings, single dots representing the current directory, double dots indicating parent directories, or forward slashes were not rejected. Consequently, if a malicious actor controls or compromises a package repository index, they can inject these unsafe values into the bundlefile attribute. During the subsequent download and write operations, the application interprets these characters as path navigation instructions rather than literal filename components.
This flaw leads to a directory traversal vulnerability that allows for arbitrary file writes outside of the intended cache location. By using sequences such as ../../ or /etc/, an attacker can direct the package manager to overwrite system files in sensitive directories like /bin, /usr/lib, or configuration folders within /etc. The operational impact is severe, potentially resulting in remote code execution if critical binaries are replaced with malicious payloads, privilege escalation through modification of setuid programs, or complete system compromise by altering security configurations. This type of attack undermines the integrity and availability guarantees provided by package management systems, which users typically trust to handle software installation securely without requiring root-level intervention for every step.
From a classification perspective, this vulnerability aligns with CWE-22: Improper Limitation of a Pathname to a Restricted Directory, as it involves path traversal leading to access outside the restricted directory. It also relates to CWE-73: External Control of File Name or Path, where user-controllable input influences file operations without proper sanitization. In terms of offensive security frameworks, this behavior corresponds to ATT&CK technique T1059.004: Unix Shell Commands via Package Management Systems, although the primary vector here is supply chain compromise leading to arbitrary write capabilities rather than direct command execution at the time of vulnerability exploitation. The ultimate goal would be code execution after successful file overwrite.
Mitigation strategies primarily involve upgrading mport to version 2.7.8 or later, where the developers have implemented rigorous input validation checks for bundle filenames before they are used in path construction. System administrators should ensure that their package repositories are trusted and signed to prevent injection of malicious index data from compromised sources. Additionally, implementing file integrity monitoring on critical system directories can help detect unauthorized modifications resulting from such exploits. For environments where immediate patching is not feasible, restricting network access to only verified and secure repository mirrors reduces the risk surface associated with fetching untrusted metadata.