CVE-2025-6196 is a medium-severity vulnerability identified in libgepub, a library responsible for parsing EPUB files. The flaw arises from improper handling of file size calculations when processing specially crafted EPUB files, leading to an integer overflow or wraparound condition. This miscalculation results in incorrect memory allocation sizes, which can cause the affected application to crash. The vulnerability primarily manifests as a denial of service (DoS) condition due to application crashes triggered by malformed EPUB content. A notable affected component is Tumbler, a desktop service that automatically processes files in directories, including EPUB files, potentially exposing users to crashes when browsing folders containing maliciously crafted EPUBs. Although no direct remote exploitation vector has been confirmed, any application leveraging libgepub to parse user-supplied EPUB files could be vulnerable if it processes untrusted content. The CVSS 3.1 base score is 5.5 (medium), reflecting that the attack vector is local (AV:L), requires low attack complexity (AC:L), no privileges (PR:N), but does require user interaction (UI:R). The impact is limited to availability (A:H) with no confidentiality or integrity impact. The vulnerability affects Red Hat Enterprise Linux 7 among other possible platforms using libgepub. No known exploits are currently in the wild, and no patches are explicitly linked in the provided data, indicating the need for vigilance and proactive mitigation by affected users and organizations.

For European organizations, the primary impact of CVE-2025-6196 is the potential for denial of service conditions in desktop environments or services that automatically parse EPUB files, such as document management systems, digital libraries, or user workstations running affected Linux distributions like Red Hat Enterprise Linux 7. This could disrupt normal operations, especially in sectors relying on automated document processing or digital content management. While the vulnerability does not compromise confidentiality or integrity, repeated crashes could lead to productivity loss, increased support costs, and potential cascading failures if critical services depend on EPUB parsing. Organizations with workflows involving EPUB content ingestion or browsing should be aware of this risk. The lack of remote exploitation vectors limits the threat to local or user-initiated scenarios, reducing the risk of widespread remote attacks but emphasizing the need for endpoint security and user awareness.

To mitigate CVE-2025-6196, European organizations should: 1) Identify and inventory systems using libgepub, especially those running Red Hat Enterprise Linux 7 or similar environments. 2) Monitor vendor advisories for patches or updates to libgepub and apply them promptly once available. 3) Implement application whitelisting or sandboxing for applications that automatically process EPUB files, such as Tumbler, to contain potential crashes and prevent system-wide impact. 4) Educate users to avoid opening or browsing directories containing untrusted or unsolicited EPUB files, reducing the likelihood of triggering the vulnerability. 5) Consider disabling or restricting automatic thumbnailing or metadata extraction services that process EPUB files if they are not essential. 6) Employ endpoint detection and response (EDR) solutions to monitor for abnormal application crashes or behaviors related to EPUB processing. 7) For critical environments, consider alternative EPUB parsing libraries or tools with no known vulnerabilities until patches are released.