CVE-2026-71219

A stack overflow vulnerability was found in gfs2-utils. The hash table traversal code in metawalk.c uses alloca() with an exponentially-derived size from the untrusted on-disk di_depth field without bounds validation. A crafted GFS2 filesystem image with a large di_depth value causes stack exhaustion and a denial of service when processed by fsck.gfs2, gfs2_edit, or savemeta.

This vulnerability is assessed as Moderate impact because the alloca-based stack exhaustion results in a process crash (SIGSEGV) rather than controlled memory corruption. RHEL stack guard pages (1MB gap, post-CVE-2017-1000364) prevent the overflow from reaching heap or other mapped memory, confining the impact to denial of service against the gfs2-utils process. Exploitation requires local access and user interaction: an administrator must run a gfs2-utils tool (fsck.gfs2, gfs2_edit, or savemeta) on a crafted GFS2 filesystem image. The vulnerability does not affect the kernel GFS2 driver, which validates di_depth in gfs2_dinode_in().

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Run gfs2-utils tools in a containerized or VM-isolated environment when processing potentially compromised or untrusted GFS2 filesystem images. Disable automatic fsck at boot for GFS2 filesystems until patches are applied by setting fs_passno to 0 in /etc/fstab. Use ulimit -s to reduce the stack size limit, converting potential exploitation into a controlled crash.