CVE Catalog

CVE-2026-31452

HighCVSS 7.8
Published: Updated: Translated: NVD NIST

Exploitation Probability (EPSS)

Low risk
0.13%

3th percentile - higher than 3% of all known CVEs

Summary

A vulnerability in the Linux kernel's ext4 filesystem occurs when truncate() grows a file beyond inline data capacity without converting to extent-based storage. This leaves the inline flag set while the file size exceeds inline capacity, causing a BUG_ON() on subsequent write attempts.

Risk Assessment

A local attacker can trigger a kernel panic via a crafted file operation sequence, leading to a denial of service (DoS) for the entire system.

Recommendation

Immediately update the Linux kernel to a version containing the fix (commit adding a check in ext4_setattr() and inline-to-extent conversion).

Other vulnerabilities in Linux kernel

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Original NVD description (English source)

In the Linux kernel, the following vulnerability has been resolved: ext4: convert inline data to extents when truncate exceeds inline size Add a check in ext4_setattr() to convert files from inline data storage to extent-based storage when truncate() grows the file size beyond the inline capacity. This prevents the filesystem from entering an inconsistent state where the inline data flag is set but the file size exceeds what can be stored inline. Without this fix, the following sequence causes a kernel BUG_ON(): 1. Mount filesystem with inode that has inline flag set and small size 2. truncate(file, 50MB) - grows size but inline flag remains set 3. sendfile() attempts to write data 4. ext4_write_inline_data() hits BUG_ON(write_size > inline_capacity) The crash occurs because ext4_write_inline_data() expects inline storage to accommodate the write, but the actual inline capacity (~60 bytes for i_block + ~96 bytes for xattrs) is far smaller than the file size and write request. The fix checks if the new size from setattr exceeds the inode's actual inline capacity (EXT4_I(inode)->i_inline_size) and converts the file to extent-based storage before proceeding with the size change. This addresses the root cause by ensuring the inline data flag and file size remain consistent during truncate operations.

Vulnerability data from NVD (NIST) · CISA KEV · EPSS