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

> A race condition in the Linux kernel RDS TCP module allows a use-after-free via concurrent sysctl writes during network namespace teardown, potentially leading to privilege escalation.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 10 Aug 2026
- **Updated:** 21 Oct 2026
- **Also known as:** BELL-CVE-2026-68290, DEBIAN-CVE-2026-68290, GHSA-j86x-f498-4jqp, UBUNTU-CVE-2026-68290

## What is CVE-2026-68290?

CVE-2026-68290 is a high-severity use after free vulnerability in Linux, published on 10 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official 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.

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2026-68290?


## How do I fix CVE-2026-68290?

Apply the vendor's patch.

## Is CVE-2026-68290 being exploited?

There is no known exploitation of CVE-2026-68290 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-68290 and fix it if it is affected.

What it is: CVE-2026-68290 is a high-severity use after free vulnerability in Linux, published on 10 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-68290 in the wild and no public exploit code.

Affected product: Linux. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-68290/ (Markdown: https://insights.sbomify.com/CVE-2026-68290/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-68290
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-68290
- OSV: https://osv.dev/vulnerability/CVE-2026-68290

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-68290/
Summaries are generated and may contain mistakes; the official description above is the record.