CVE-2026-71221 in Red Hat
Summary
by MITRE • 09/03/2026
A stack out-of-bounds write vulnerability was found in gfs2-utils. In savemeta, the height value from on-disk inode metadata is used as a loop bound without bounds checking, causing a stack buffer overflow that may lead to arbitrary code execution when processing crafted GFS2 filesystem images.
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Analysis
by VulDB Data Team • 09/03/2026
The identified vulnerability resides within the gfs2-utils package, specifically affecting the savemeta utility which is responsible for saving metadata from GFS2 filesystems. This critical flaw manifests as a stack-based out-of-bounds write condition triggered by improper validation of input data derived directly from on-disk inode structures. The core technical deficiency lies in the handling of the height value extracted during the parsing of these inode metadata blocks. Instead of performing rigorous bounds checking to ensure that this value falls within acceptable limits for array indexing or buffer allocation, the software utilizes it unconditionally as a loop bound. This lack of validation allows an attacker who controls the contents of the GFS2 filesystem image to manipulate the height field such that it exceeds the allocated stack space reserved by the application logic.
When savemeta processes a maliciously crafted GFS2 filesystem image containing an excessively large or malformed height value, the resulting loop iteration count causes writes beyond the boundaries of the designated stack buffer. This overflow overwrites adjacent memory locations on the call stack, potentially corrupting critical control data such as return addresses and saved frame pointers. In modern operating systems with standard security mitigations like non-executable stacks, this corruption might result in a denial of service through application crash due to segmentation faults or invalid instruction pointer values. However, if specific exploitation techniques are employed, such as stack canary bypasses or partial overwrites targeting function pointers within the same memory region, an attacker may achieve arbitrary code execution with the privileges of the user running the savemeta utility.
The operational impact of this vulnerability is significant for administrators and automated systems that process GFS2 filesystem images from untrusted sources. Since savemeta is often used in backup, migration, or forensic analysis scenarios, exposure to maliciously constructed disk images could lead to complete system compromise if executed with elevated privileges. The attack vector primarily involves supplying a crafted file rather than network-based interaction, classifying this as an input validation failure where the software fails to distinguish between valid and invalid metadata structures before processing them. This aligns closely with CWE-121, which describes stack buffer overflow vulnerabilities arising from insufficient bounds checking on user-controlled or externally influenced data inputs.
From a threat intelligence perspective, this vulnerability can be mapped to MITRE ATT&CK techniques related to initial access and execution via malicious files. Specifically, it relates to the exploitation of software bugs for code execution, often categorized under T1203 if leveraged in conjunction with other exploit chains or simply as a standalone flaw leading to privilege escalation depending on context. The absence of boundary checks represents a fundamental deviation from secure coding practices recommended by industry standards such as OWASP and CERT C Coding Standards, which emphasize the necessity of validating all external inputs against expected ranges before use in memory operations.
Mitigation strategies should focus primarily on updating gfs2-utils to versions where this issue has been patched with proper input validation logic that verifies the height value against known maximum limits for GFS2 inode structures prior to its usage as a loop counter. Until patches are applied, administrators should restrict access to savemeta and avoid processing filesystem images from untrusted or unknown origins. Additionally implementing strict file integrity monitoring and least privilege principles can reduce the blast radius if exploitation occurs. Developers reviewing similar code paths in other utilities within the gfs2-utils suite should audit for analogous patterns of unchecked integer usage derived directly from disk metadata to prevent recurrence of this class of memory corruption vulnerabilities across related tools.