The Linux kernel’s OCFS2 filesystem previously lacked a check that rejects non‑inline dinodes that declare a non‑zero size while having zero allocated clusters. A malformed dinode satisfying this invalid state could cause the filesystem to read or write beyond allocated storage, repeat failures while traversing directories, and potentially corrupt file metadata or silently drop access to data. The effect is a loss of data integrity and, in worst‑case scenarios, a denial of service for applications relying on the affected filesystem. The weakness, a failure to enforce correct size/extent limits, is reflected by CWE‑606 and can manifest as a logical error in input handling.

The issue manifests in any Linux kernel that contains the OCFS2 driver before the internal check was added. Systems using the default OCFS2 volume, especially those mounted without the OCFS2_FEATURE_INCOMPAT_SPARSE_ALLOC flag, are susceptible. All releases prior to the kernel update that introduces the reject check are affected; the exact minor revisions are not listed in the advisory.

The likely attack vector is local modification of OCFS2 on‑disk structures, which is inferred from the requirement to craft a malformed dinode. The CVSS score for this vulnerability is 5.5, indicating moderate severity. Its EPSS score is less than 1% and it is not listed in the CISA KEV catalog, suggesting no known active exploitation. An attacker with local or root access who can manipulate OCFS2 storage may craft a malformed dinode that matches the invalid size-with-zero-clusters state, causing the kernel to read or traverse beyond allocated storage. This can lead to data corruption or a denial of service for applications using the affected filesystem. The exploit requires local modification of on‑disk structures, so the risk remains moderate to high for environments that expose such capabilities.