CVE-2025-53367 is a high-severity vulnerability affecting DjVuLibre, a GPL-licensed implementation of the DjVu document and image format widely used for web-centric document distribution. The vulnerability exists in versions prior to 3.5.29 within the MMRDecoder::scanruns method. Specifically, the issue is an out-of-bounds (OOB) write caused by the failure to ensure that the 'xr' pointer remains within the allocated buffer boundaries. This improper bounds checking allows writes beyond the allocated heap memory, leading to heap corruption. Additionally, an out-of-bounds read is possible via the 'pr' pointer for the same reason. Heap corruption vulnerabilities can be exploited to execute arbitrary code, cause denial of service, or crash applications processing maliciously crafted DjVu files. The vulnerability does not require privileges or authentication but does require user interaction, as it is triggered when a vulnerable application processes a malicious DjVu document. The CVSS 4.0 base score is 8.4, reflecting high impact on confidentiality, integrity, and availability, with local attack vector and low attack complexity. No known exploits are currently reported in the wild, but the vulnerability is critical due to the potential for remote code execution or application crashes in software that processes DjVu files. The issue has been patched in version 3.5.29, and users are strongly advised to upgrade to this or later versions to mitigate the risk.

For European organizations, the impact of this vulnerability can be significant, especially for entities relying on DjVuLibre for document management, archival, or distribution. Sectors such as publishing, libraries, government agencies, and educational institutions that handle DjVu files may be exposed. Exploitation could lead to unauthorized code execution, data breaches, or disruption of document processing workflows. Given the high confidentiality, integrity, and availability impact, attackers could leverage this vulnerability to compromise sensitive documents or disrupt critical services. The requirement for user interaction means phishing or social engineering could be used to deliver malicious DjVu files. The absence of known exploits currently provides a window for proactive patching, but the potential for future exploitation necessitates urgent attention. Organizations processing untrusted DjVu files from external sources are particularly at risk.

1. Immediate upgrade to DjVuLibre version 3.5.29 or later to apply the official patch addressing the out-of-bounds write vulnerability. 2. Implement strict input validation and sandboxing for applications that process DjVu files to limit the impact of potential exploitation. 3. Employ endpoint protection solutions capable of detecting anomalous behavior or heap corruption patterns during document processing. 4. Educate users about the risks of opening unsolicited or unexpected DjVu documents, especially from untrusted sources, to reduce the likelihood of successful social engineering. 5. Monitor network and endpoint logs for unusual crashes or suspicious activity related to document processing applications. 6. If upgrading immediately is not feasible, consider disabling or restricting the use of DjVu file processing in critical environments until patched. 7. Incorporate DjVu file scanning into existing malware detection pipelines to identify potentially crafted malicious files.