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VulnerabilityPublished Updated

CVE-2026-68148: Linux kernel · fscrypt: Add missing superblock check in find_or_insert_direct_key()

Affects Linux kernelSource CVE Database V5

0

Not known to be exploited · CVSS 7.8 High · fixed in deff41898a5ae3a47db5fa1896a494aa95efda5d : patch Linux kernel soon.

Data as of 26 Oct 2026, 14:05 UTC

CVSS 3.1 base score
7.8High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.09% chance of exploitation in 30 days – higher than 0% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CISA SSVC
Exploitation
No evidence of active exploitation and no public proof of concept
Automatable
Attackers cannot reliably automate steps 1–4 of the kill chain
Technical impact
Total control over the software or total information disclosure

CISA SSVC assessment, 2026-10-16.

Patch
Available – fixed in deff41898a5ae3a47db5fa1896a494aa95efda5d, b5fa40226e71c17847b9ff2816c6ca4133d0d994, 330249609b70778094a7a36f5b6bcfa6362121d4 +3
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 10 Aug 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

ProductAffectedFixed in
LinuxLinuxAffected
  • ≥ 22e9947a4b2ba255888541bd0111cf00b9b16586, < deff41898a5ae3a47db5fa1896a494aa95efda5d
Fixed in
  • deff41898a5ae3a47db5fa1896a494aa95efda5d
LinuxLinuxAffected
  • ≥ 22e9947a4b2ba255888541bd0111cf00b9b16586, < b5fa40226e71c17847b9ff2816c6ca4133d0d994
Fixed in
  • b5fa40226e71c17847b9ff2816c6ca4133d0d994
LinuxLinuxAffected
  • ≥ 22e9947a4b2ba255888541bd0111cf00b9b16586, < 330249609b70778094a7a36f5b6bcfa6362121d4
Fixed in
  • 330249609b70778094a7a36f5b6bcfa6362121d4
LinuxLinuxAffected
  • ≥ 22e9947a4b2ba255888541bd0111cf00b9b16586, < 95376fe9c145be35566991df99c53134943d992f
Fixed in
  • 95376fe9c145be35566991df99c53134943d992f
LinuxLinuxAffected
  • ≥ 22e9947a4b2ba255888541bd0111cf00b9b16586, < 965b5bc8cf5031225e057979ce660fec2bd5fbfc
Fixed in
  • 965b5bc8cf5031225e057979ce660fec2bd5fbfc
LinuxLinuxAffected
  • ≥ 22e9947a4b2ba255888541bd0111cf00b9b16586, < 466f187b501a5ac8e1ea2ccf3ccd5c46108d8830
Fixed in
  • 466f187b501a5ac8e1ea2ccf3ccd5c46108d8830

Description

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.

References

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