---
id: "CVE-2026-99136"
kind: "vulnerability"
aliases: ["CVE-2026-99136"]
title: "Linux kernel dm-crypt: race can report failed I/O as successful"
severity: "low"
cvss: null
epss: null
exploited: false
status: "open"
category: "runtime"
products: []
ecosystems: []
tags: ["dm-crypt", "linux-kernel", "luks", "runtime", "self-hosted"]
not_affected_if: ["no-dm-crypt"]
published_at: "2026-10-28T11:17:33+00:00"
first_seen_at: "2026-10-28T11:32:35+00:00"
updated_at: "2026-10-28T11:36:11+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-99136", "first_seen_at": "2026-10-28T11:32:35+00:00"}]
---

# Linux kernel dm-crypt: race can report failed I/O as successful

In the Linux kernel's dm-crypt disk encryption layer, a race in crypt_dec_pending can read a stale error status before the final reference drop, so a failed read or write gets completed as successful. The impact is data-integrity: an application may treat failed or undecrypted data as valid, and the sources describe no code execution.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Check the running kernel with `uname -r` and whether dm-crypt is in use with `dmsetup table` or `lsblk -o NAME,TYPE` showing `crypt` devices.
- Compare the kernel version against the fixed stable release listed in the NVD entry (unknown from the sources).

## Fix

- Update to a Linux kernel release that includes the upstream commit fixing crypt_dec_pending (version unknown from the sources).
- Use your distribution's kernel update for the stable branch you run.

## Timeline

- 2026-10-28T11:32:35+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-99136

## From the sources

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

dm-crypt: fix a tiny race condition in crypt_dec_pending

crypt_dec_pending reads io->error before calling atomic_dec_and_test.
Another context, for example crypt_endio called from an interrupt, may
set io->error and drop its reference between the read and the
decrement. crypt_dec_pending then drops the last reference and completes
the bio with the stale status - so a read that failed and was never
decrypted, or a write that failed, is reported as successful.

The read was placed before the decrement by commit b35f8caa0890 ("dm
crypt: wait for endio to complete before destruction"), because that
commit freed dm_crypt_io before calling bio_endio. This is no longer the
case, dm_crypt_io lives in the per-bio data now.

Read io->error after atomic_dec_and_test instead. atomic_dec_and_test is
fully ordered, so no additional barrier is needed.

---

_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_