CVE-2026-46124: Linux Kernel

High severity, CVSS 7.5. EPSS: 0.6% chance of exploitation in the next 30 days.

In the Linux kernel, the following vulnerability has been resolved: isofs: validate block number from NFS file handle in isofs_export_iget isofs_fh_to_dentry() and isofs_fh_to_parent() pass an attacker- controlled block number (ifid->block or ifid->parent_block) from the NFS file handle to isofs_export_iget(), which only rejects block == 0 before calling isofs_iget() and ultimately sb_bread(). A crafted file handle with fh_len sufficient to pass the check added by commit 0405d4b63d08 ("isofs: Prevent the use of too small fid") can still drive the server to read any in-range block on the backing device as if it were an iso_directory_record. That earlier fix was assigned CVE-2025-37780. sb_bread() on an out-of-range block returns NULL cleanly via the EIO path, so there is no memory-safety violation. For in-range reads of adjacent-partition data on the same block device, the unrelated bytes end up in iso_inode_info fields that reach the NFS client as dentry metadata. The deployment surface (isofs exported over NFS from loop-mounted images) is narrow and requires an authenticated NFS peer, but the malformed-file-handle class is reportable as hardening next to the existing CVE-2025-37780 fix. Reject block >= ISOFS_SB(sb)->s_nzones in isofs_export_iget() so the check covers both isofs_fh_to_dentry() and isofs_fh_to_parent() call sites with a single line.

Affected products

• Linux Linux Kernel: from 5.4.293, before 5.5 (fixed in 5.5); from 5.10.237, before 5.10.258 (fixed in 5.10.258); from 5.15.181, before 5.15.209 (fixed in 5.15.209); from 6.1.135, before 6.1.175 (fixed in 6.1.175); from 6.6.88, before 6.6.140 (fixed in 6.6.140); from 6.12.25, before 6.12.88 (fixed in 6.12.88); …

Published 2026-05-28. Last modified 2026-06-24.