CVE-2022-46285 in libXpm
Summary
by MITRE • 02/07/2023
A flaw was found in libXpm. This issue occurs when parsing a file with a comment not closed; the end-of-file condition will not be detected, leading to an infinite loop and resulting in a Denial of Service in the application linked to the library.
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Analysis
by VulDB Data Team • 03/06/2023
The vulnerability identified as CVE-2022-46285 resides within the libXpm library, a component commonly used for handling X11 Pixmap (XPM) image format processing in Unix-like operating systems and applications. This flaw represents a classic denial of service condition that can be triggered through improper handling of malformed input data. The issue specifically manifests when the library encounters an XPM file containing an unclosed comment structure, which creates a parsing anomaly that fundamentally disrupts the normal execution flow of the application. The library's parser fails to properly detect the end-of-file condition when processing such malformed input, leading to a condition where the parsing loop continues indefinitely without proper termination.
The technical root cause of this vulnerability can be categorized under CWE-835, which describes the condition where a loop has no valid exit mechanism, resulting in an infinite loop or infinite recursion. This occurs because the XPM parser implementation lacks proper boundary checking for comment termination sequences within the file structure. When a comment is opened with the standard / delimiter but not properly closed with /, the parser enters a state where it continuously attempts to read and process what it perceives as valid data while never reaching the actual end of the file. The parser's state machine becomes trapped in a cycle where it cannot distinguish between legitimate data continuation and an infinite comment parsing loop, effectively creating a denial of service condition that consumes system resources indefinitely.
From an operational perspective, this vulnerability poses significant risks to applications that rely on libXpm for image processing, particularly those handling user-provided or externally sourced XPM files. The denial of service impact extends beyond simple application crashes, as the infinite loop consumes CPU cycles and memory resources, potentially leading to system-wide performance degradation or complete service unavailability. Applications that process multiple files or operate in multi-threaded environments face amplified risks, as a single malicious or malformed XPM file can compromise the entire processing pipeline. This vulnerability is particularly concerning in server environments where applications might be processing untrusted input from remote users or automated systems, creating potential attack vectors for resource exhaustion attacks.
The mitigation strategies for this vulnerability should encompass multiple layers of defense to protect against exploitation. Immediate patching of the libXpm library to implement proper comment termination detection and end-of-file boundary checking represents the primary remediation approach. System administrators should also implement input validation mechanisms that scan for malformed XPM files before processing, particularly in environments where user uploads are permitted. Additionally, implementing resource limits and timeout mechanisms for file processing operations can help contain the impact of any exploitation attempts. From a defensive standpoint, monitoring for unusual CPU consumption patterns or extended processing times when handling image files can serve as early warning indicators of potential exploitation attempts. The vulnerability aligns with ATT&CK technique T1499.004, which describes resource exhaustion attacks targeting application availability, and represents a common pattern of denial of service vulnerabilities in parsing libraries that lack proper input sanitization and boundary condition handling.