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Vulnerabilities
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CVE-2026-46124

Updated on 28 May 2026

Severity

7.5 High severity

Details

CVSS score
7.5
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Links
NISTCIRCLRHELUbuntu

Overview

About vulnerability

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.

Details

Affected product:
Ubuntu 20.04 ELS
Affected packages:
linux-meta @ 5.4.0 (+1 more)

Fixes

KernelCare state

Live-patch status from KernelCare for each operating system.

Operating system Status Covered kernels
Amazon Linux 2023 Planned —
Debian 11 In Rollout
3 kernels
  • 5.10.237-1
  • 5.10.244-1
  • 5.10.247-1
Debian 11 cloud In Rollout
3 kernels
  • 5.10.237-1
  • 5.10.244-1
  • 5.10.247-1
Debian 12 In Rollout
40 kernels
  • 6.1.38-1
  • 6.1.38-2
  • 6.1.38-4
  • 6.1.52-1
  • 6.1.55-1
  • 6.1.64-1
  • 6.1.66-1
  • 6.1.69-1
  • 6.1.76-1
  • 6.1.27-1
  • 6.1.67-1
  • 6.1.85-1
  • 6.1.90-1
  • 6.1.94-1
  • 6.1.99-1
  • 6.1.106-3
  • 6.1.112-1
  • 6.1.115-1
  • 6.1.119-1
  • 6.1.123-1
  • 6.1.128-1
  • 6.1.124-1
  • 6.1.129-1
  • 6.1.133-1
  • 6.1.135-1
  • 6.1.137-1
  • 6.1.140-1
  • 6.1.139-1
  • 6.1.147-1
  • 6.1.148-1
  • 6.1.153-1
  • 6.1.158-1
  • 6.1.159-1
  • 6.1.162-1
  • 6.1.164-1
  • 6.1.170-1
  • 6.1.170-3
  • 6.1.172-1
  • 6.1.174-1
  • 6.1.170-2
Debian 13 Released
7 kernels
  • 6.12.85-1
  • 6.12.86-1
  • 6.12.73-1
  • 6.12.63-1
  • 6.12.69-1
  • 6.12.74-1
  • 6.12.74-2
Ubuntu 22.04 Planned —
Ubuntu 24.04 Planned —