CVE-2025-61146 identifies a memory leak vulnerability in the saitoha libsixel library, a tool commonly used for converting images into sixel format for terminal display. The vulnerability resides in the malloc_stub.c component, where memory allocated during processing is not properly freed, causing a gradual increase in memory consumption. This can lead to resource exhaustion, potentially degrading system performance or causing application crashes. While the vulnerability does not directly allow code execution or privilege escalation, the memory leak can be exploited in denial-of-service (DoS) attacks by feeding specially crafted or large image inputs to applications using vulnerable libsixel versions (up to 1.8.7). The leak's exploitation requires the attacker to supply input processed by libsixel, which may or may not require user interaction depending on the application context. No patches or fixes are currently linked, and no known exploits have been reported in the wild. Given the library's use in various open-source projects and embedded systems, the vulnerability poses a moderate risk until remediated. The lack of a CVSS score requires an assessment based on the potential impact on availability and the ease of exploitation through crafted inputs.

The primary impact of this vulnerability is on system availability due to memory exhaustion. Applications or systems using vulnerable libsixel versions may experience degraded performance, crashes, or denial of service when processing malicious or malformed image data. This can disrupt services relying on image rendering or conversion, particularly in embedded devices, terminal emulators, or multimedia tools that incorporate libsixel. While confidentiality and integrity are not directly compromised, the operational disruption can affect business continuity and user experience. Organizations with automated image processing pipelines or remote image rendering services are at higher risk. The absence of known exploits reduces immediate threat but does not eliminate future risk, especially as attackers may develop exploitation techniques targeting this flaw. The impact scope is limited to environments where libsixel is actively used, but given its presence in open-source ecosystems, the affected base could be broad in certain sectors.

To mitigate this vulnerability, organizations should first identify all systems and applications using libsixel up to version 1.8.7. Until a patch is released, restrict the processing of untrusted or unauthenticated image inputs through libsixel to reduce exposure. Implement resource usage monitoring and limits (e.g., memory quotas, cgroups) on processes that utilize libsixel to detect and contain abnormal memory consumption. Consider sandboxing or isolating these processes to prevent system-wide impact. Engage with the libsixel maintainers or community to obtain updates or patches addressing the memory leak. Additionally, review application code for proper input validation and error handling when dealing with image data. Incorporate runtime protections such as AddressSanitizer or memory leak detection tools during development and testing to identify similar issues proactively. Finally, maintain an incident response plan to quickly address potential denial-of-service conditions stemming from this vulnerability.