The vulnerability exists in the isofs subsystem of the Linux kernel, where the fast path for handling an empty Zisofs block incorrectly calculates the byte count relative to the page offset. This miscalculation causes an out-of-bounds array access in zisofs_read_folio when a compressed ISO9660 image is read. An attacker could exploit the bug to read memory beyond the intended buffer, potentially leaking sensitive kernel data or executing arbitrary code with kernel privileges.

The flaw affects any system running the Linux kernel that includes the isofs filesystem support before the patch that corrects the page array handling. Versions of the kernel that use the zisofs transparent decompression path prior to the repository commit that removes the bug are susceptible. The lack of specific version numbers means the vulnerability applies to all affected releases until the patch is applied.

The issue is triggered by a normal file read of a Zisofs-compressed ISO9660 image, which can be executed locally by any user with access to such a file. Although the EPSS score is reported as less than 1% and the vulnerability is not listed in CISA memory corruption could lead to privilege escalation or denial of service. The CVSS score was not provided in the advisory, but the nature of the bug and its local execution vector indicate a high risk for systems that mount or read susceptible images.