CVE-2026-88842 in BusyBox
Summary
by MITRE • 10/14/2026
A flaw was found in BusyBox dpkg. The write_status_file() function does not reset a field cursor between package stanzas. When two packages are removed in a single invocation and the first stanza is larger than the second, the second package stanza can be dropped from the status file, causing limited data corruption.
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Analysis
by VulDB Data Team • 10/14/2026
The vulnerability identified within BusyBox dpkg stems from an improper handling of state management during the processing of multiple package stanzas in the status file. Specifically, the write_status_file() function fails to reset a field cursor or clear residual data between consecutive package entries when performing removal operations. This logic error creates a scenario where the internal pointer used for writing package information does not properly align with the start of the new stanza if the preceding entry was larger than the current one being processed. Consequently, when two packages are removed in a single invocation and the first package's data footprint exceeds that of the second, the residual bytes from the first entry overwrite or obscure parts of the second entry during the write operation. This results in incomplete or corrupted data for the second package within the status file, effectively dropping critical metadata associated with that package.
From a technical perspective, this flaw represents an improper state management issue where internal variables are not properly initialized or reset between iterative operations on similar data structures. The root cause lies in the assumption that writing smaller subsequent entries will naturally fit into the space left by larger preceding ones without explicit truncation or cursor adjustment. In reality, because dpkg status files are often treated as append-only or fixed-length record sets depending on implementation details, failing to clear the buffer leads to data persistence from previous operations bleeding into current records. This is a classic example of an improper neutralization issue where input boundaries and internal state transitions are not strictly enforced during file I/O operations.
The operational impact of this vulnerability is primarily limited to local system integrity rather than remote code execution or privilege escalation, given the nature of BusyBox dpkg as a package management utility typically run with elevated privileges but interacting only with local filesystem structures. However, the data corruption can lead to significant administrative and security consequences. If critical metadata for a removed package remains partially present in an inconsistent state, subsequent package manager operations may fail, leading to broken dependencies or inability to reinstall packages correctly. In worst-case scenarios, if other tools parse this corrupted status file expecting valid JSON-like or structured text formats, they might encounter parsing errors that could be exploited for denial of service against system management scripts. Furthermore, the inconsistency between actual installed state and recorded state can mask whether a package is truly removed, potentially leaving residual configuration files or triggers active when they should have been cleaned up, thereby increasing the attack surface through lingering artifacts.
This vulnerability aligns with CWE-672, which describes the use of operations on data without proper neutralization, specifically regarding improper handling of internal state during sequential processing. It also relates to CWE-190, as integer or buffer size miscalculations often underpin such off-by-one or residual data issues in C-based utilities like BusyBox. From a tactical standpoint within the MITRE ATT&CK framework, this flaw does not directly facilitate initial access but could be leveraged during post-exploitation phases to maintain persistence by ensuring certain packages remain installed despite removal attempts, or to cause denial of service against system maintenance routines that rely on accurate package status data.
Mitigation strategies should focus primarily on applying the vendor-provided patch as soon as it becomes available, which corrects the cursor reset logic in write_status_file(). Administrators running BusyBox dpkg should verify their version and apply updates from trusted sources to ensure this state management flaw is resolved. In environments where immediate patching is not feasible, monitoring for anomalies in package manager logs or unexpected behavior during bulk removal operations can serve as a detection mechanism. Additionally, implementing integrity checks on the /var/lib/dpkg/status file through regular automated validation scripts can help identify corruption early before it cascades into broader system instability. Regular backups of critical configuration directories also provide a recovery path should data corruption occur due to this or similar vulnerabilities in package management tools.