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CVE-2026-68148

Updated on 10 Aug 2026

Severity

7.8 High severity

Details

CVSS score
7.8
CVSS vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Links
NISTCIRCLRHELUbuntu

Overview

About vulnerability

In the Linux kernel, the following vulnerability has been resolved:

fscrypt: Add missing superblock check in find_or_insert_direct_key()

The legacy ‘fscrypt_direct_keys’ table caches master keys that are used by v1 encryption policies that have FSCRYPT_POLICY_FLAG_DIRECT_KEY. It’s just a global table for all filesystems (since the keys can be provided by the legacy process-subscribed keyrings mechanism, which makes it difficult to reuse super_block::s_master_keys).

The entries in it (‘struct fscrypt_direct_key’) do contain a super_block pointer, though, for passing to fscrypt_destroy_inline_crypt_key() when the last inode that references the key is evicted.

However, when finding the fscrypt_direct_key for an inode, we weren’t actually comparing the super_block pointer. As a result, inodes with different super_blocks could point to the same fscrypt_direct_key. That could extend the lifetime of a fscrypt_direct_key beyond the super_block it points to, causing a use-after-free later.

Fix this by creating distinct fscrypt_direct_key structs for distinct super_block structs.

Note that this problem doesn’t exist in the v2 policy equivalent (“per-mode keys”), since the data structures there are per super_block.

Details

Affected product:
AlmaLinux 9.2 ESU , Debian 10 ELS , TuxCare 9.6 ESU , TuxCare 9.8 ESU
Affected packages:
linux @ 4.19.0 (+3 more)

Fixes

KernelCare state

Live-patch status from KernelCare for each operating system.

Operating system Status Covered kernels
Debian 12 Released
43 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
  • 6.1.176-1
  • 6.1.177-1
  • 6.1.180-1
Debian 13 Released
14 kernels
  • 6.12.85-1
  • 6.12.86-1
  • 6.12.88-1
  • 6.12.74-2
  • 6.12.73-1
  • 6.12.63-1
  • 6.12.69-1
  • 6.12.74-1
  • 6.12.90-1
  • 6.12.90-2
  • 6.12.94-1
  • 6.12.95-1
  • 6.12.96-1
  • 6.12.100-1
Ubuntu 24.04 Planned —
Ubuntu 24.04 AWS Planned —
Ubuntu 26.04 Will Not Fix —