CVE-2026-71220: Out-of-bounds Write in Red Hat Red Hat Enterprise Linux 7

CVE-2026-71220 is a stack buffer overflow vulnerability in gfs2-utils' gfs2_edit tool on Red Hat Enterprise Linux 7. The di_height field from on-disk inode metadata is used as an array index without bounds checking, enabling a stack out-of-bounds write. This can overwrite the return address on the stack, potentially allowing arbitrary code execution. Exploitation requires local access and user interaction, as an administrator must run gfs2_edit on a crafted GFS2 filesystem image. The kernel GFS2 driver is not affected because it validates di_height properly. Compiler hardening features such as stack protector, PIE, and ASLR provide partial mitigation. Red Hat rates the impact as moderate but assigns a CVSS v3.1 score of 7.0 (high severity).

The vulnerability allows a local attacker with user interaction to cause a stack buffer overflow in gfs2_edit, potentially leading to arbitrary code execution with the privileges of the user running the tool. The impact includes confidentiality, integrity, and availability compromise. However, exploitation requires local access and an administrator to run gfs2_edit on a crafted filesystem image. The kernel GFS2 driver is unaffected, limiting the scope of impact. Compiler hardening mitigations reduce but do not eliminate the risk.

Red Hat advises not to run gfs2_edit on untrusted or potentially compromised GFS2 filesystem images. When processing untrusted images, run gfs2-utils tools in containerized or VM-isolated environments. Additionally, disable automatic fsck at boot for GFS2 filesystems by setting fs_passno to 0 in /etc/fstab until official patches are applied. Check the Red Hat advisory for updates on patch availability and apply fixes when released.