In this vulnerability the Linux kernel rejects mounting an ext4 filesystem that uses the bigalloc feature while the s_first_data_block field is non-zero. This issue corresponds to CWE‑1288 (File System Format Validity Issue). The failure arises from an unchecked filesystem format condition that causes the mount operation to abort, leading to a denial of service for any process that requires access to the affected partition.

The flaw impacts any Linux system that runs a kernel version that does not yet include the patch that adds the check against s_first_data_block. Administrators should consider all unpatched kernels as vulnerable, especially when ext4 filesystems are created with bigalloc enabled. The CNA vendor list shows only Linux, and no specific version ranges are provided, so all legacy kernels are potentially affected.

The latest CVSS score of 7.8 classifies this issue as high severity. The flaw is recognized as CWE‑1288, a file system format validity issue. Because the EPSS score is below 1%, exploitation is currently unlikely, and the vulnerability is not listed in the CISA KEV catalog. The likely attack vector is local; an attacker with root privileges or the ability to mount filesystems can trigger a denial of service by attempting to mount a bigalloc-enabled ext4 partition where s_first_data_block is non-zero. This will abort the mount operation and render the filesystem unavailable, but does not affect confidentiality or integrity.