# CVE-2026-23419: net/rds: Fix circular locking dependency in rds_tcp_tune

> A circular locking dependency in the Linux kernel's RDS TCP module can cause a deadlock, leading to a denial of service.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 3 Apr 2026
- **Updated:** 5 Aug 2026
- **Also known as:** BELL-CVE-2026-23419, DEBIAN-CVE-2026-23419, GHSA-x244-gjj6-jc73, ROOT-OS-DEBIAN-12-CVE-2026-23419, ROOT-OS-DEBIAN-13-CVE-2026-23419, ROOT-OS-UBUNTU-2404-CVE-2026-23419, UBUNTU-CVE-2026-23419

## What is CVE-2026-23419?

CVE-2026-23419 is a high-severity vulnerability in Linux kernel, published on 3 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

In the Linux kernel, the following vulnerability has been resolved:

net/rds: Fix circular locking dependency in rds_tcp_tune

syzbot reported a circular locking dependency in rds_tcp_tune() where
sk_net_refcnt_upgrade() is called while holding the socket lock:

======================================================
WARNING: possible circular locking dependency detected
======================================================
kworker/u10:8/15040 is trying to acquire lock:
ffffffff8e9aaf80 (fs_reclaim){+.+.}-{0:0},
at: __kmalloc_cache_noprof+0x4b/0x6f0

but task is already holding lock:
ffff88805a3c1ce0 (k-sk_lock-AF_INET6){+.+.}-{0:0},
at: rds_tcp_tune+0xd7/0x930

The issue occurs because sk_net_refcnt_upgrade() performs memory
allocation (via get_net_track() -> ref_tracker_alloc()) while the
socket lock is held, creating a circular dependency with fs_reclaim.

Fix this by moving sk_net_refcnt_upgrade() outside the socket lock
critical section. This is safe because the fields modified by the
sk_net_refcnt_upgrade() call (sk_net_refcnt, ns_tracker) are not
accessed by any concurrent code path at this point.

v2:
  - Corrected fixes tag
  - check patch line wrap nits
  - ai commentary nits

Weakness: CWE-667 (Improper Locking)

## Which versions are affected by CVE-2026-23419?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-23419?

Apply the vendor's patch.

## Is CVE-2026-23419 being exploited?

There is no known exploitation of CVE-2026-23419 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-23419 and fix it if it is affected.

What it is: CVE-2026-23419 is a high-severity vulnerability in Linux kernel, published on 3 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-23419 in the wild and no public exploit code.

Affected product: Linux kernel. 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-2026-23419/ (Markdown: https://insights.sbomify.com/CVE-2026-23419/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-23419
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-23419
- OSV: https://osv.dev/vulnerability/CVE-2026-23419

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-23419/
Summaries are generated and may contain mistakes; the official description above is the record.