CVE-2026-46124isofs: validate block number from NFS file handle in isofs_export_iget

Description

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.

Timeline

Scores

EPSS (exploitation in 30 days)

0.48% · top 58% of all CVEs (12 Nov 2026)

CISA SSVC

Exploitation: none · Automatable: yes · Technical impact: partial

The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.5.

Affected products

• Linux · Linux

  • affected 5e7de55602c61c8ff28db075cc49c8dd6989d7e0 – < ee0024f5a7e3c73aa253869fae9650ae054093ca
  • affected 63d5a3e207bf315a32c7d16de6c89753a759f95a – < 31dbb4ba0f719ae7774e4c0c95172c9bf81692f5
  • affected 0fdafdaef796816a9ed0fd7ac812932d569d9beb – < 908a76f0b1038035e6ebb4f2293ce079f92e0a02
  • affected 952e7a7e317f126d0a2b879fc531b716932d5ffa – < bb0988ed4f2e26d59bbb58f644cb3a55b7521e21
  • affected 56dfffea9fd3be0b3795a9ca6401e133a8427e0b – < 0a1af74ae2177bda3aee0837a0546309aa539d0d
  • affected 0405d4b63d082861f4eaff9d39c78ee9dc34f845 – < afbafeddf23db13fe2edb2d5c0bf4bbb13d7881b
  • affected 0405d4b63d082861f4eaff9d39c78ee9dc34f845 – < 4c721a1d9b3c4fcaf59cc9b2281e3ec5a043e1a6
  • affected 0405d4b63d082861f4eaff9d39c78ee9dc34f845 – < 24376458138387fb251e782e624c7776e9826796
  • affected ee01a309ebf598be1ff8174901ed6e91619f1749
  • affected 007124c896e7d4614ac1f6bd4dedb975c35a2a8e
  • affected 5.10.237 – < 5.10.258
  • affected 5.15.181 – < 5.15.209
  • affected 6.1.135 – < 6.1.175
  • affected 6.6.88 – < 6.6.140
  • affected 6.12.25 – < 6.12.88
  • affected 5.4.293 – < 5.5
  • affected 6.14.4 – < 6.15

• Linux · Linux

  • affected 6.15
  • unaffected < 6.15
  • unaffected 5.10.258 – ≤ 5.10.*
  • unaffected 5.15.209 – ≤ 5.15.*
  • unaffected 6.1.175 – ≤ 6.1.*
  • unaffected 6.6.140 – ≤ 6.6.*
  • unaffected 6.12.88 – ≤ 6.12.*
  • unaffected 6.18.30 – ≤ 6.18.*
  • unaffected 7.0.7 – ≤ 7.0.*
  • unaffected 7.1 – ≤ *

Sources

The same CVE in the primary databases and aggregators, to check against.

• CVE.org record (opens in a new tab)
• CVE List JSON (GitHub) (opens in a new tab)
• NVD (opens in a new tab)
• FIRST EPSS (opens in a new tab)
• EUVD EUVD-2026-32883 (opens in a new tab)
• OSV.dev (opens in a new tab)
• GitHub Advisories (opens in a new tab)
• CIRCL Vulnerability-Lookup (opens in a new tab)

Badge for a README or a ticket

[![CVE-2026-46124](https://cveledger.app/badge/CVE-2026-46124.svg)](https://cveledger.app/cve/CVE-2026-46124)

Record last updated 19 Oct 2026, 19:36 UTC.