# CVE-2026-52921: netfilter: ipset: stop hash:* range iteration at end

> A flaw in Linux kernel netfilter ipset allows infinite loops during IPv4 range iteration, potentially causing denial of service.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/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:** 24 Jun 2026
- **Updated:** 24 Jun 2026
- **Also known as:** AZL-90549, BELL-CVE-2026-52921, DEBIAN-CVE-2026-52921, GHSA-3v47-mwg3-xvq2, ROOT-OS-UBUNTU-2204-CVE-2026-52921, ROOT-OS-UBUNTU-2404-CVE-2026-52921, UBUNTU-CVE-2026-52921

## What is CVE-2026-52921?

CVE-2026-52921 is a medium-severity denial of service vulnerability in Linux kernel, published on 24 Jun 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:

netfilter: ipset: stop hash:* range iteration at end

The following hash set variants:

hash:ip,mark
hash:ip,port
hash:ip,port,ip
hash:ip,port,net

iterate IPv4 ranges with a 32-bit iterator.

The iterator must stop once the last address in the requested range has
been processed. Advancing it once more can move the traversal state past
the end of the request, so a later retry may continue from an unintended
position.

Handle the iterator increment explicitly at the end of the loop and stop
once the upper bound has been processed. This keeps the existing retry
behaviour intact for valid ranges while preventing traversal from
continuing past the original boundary.

Weakness: CWE-835 (Loop with Unreachable Exit Condition)

## Which versions are affected by CVE-2026-52921?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-52921?

Apply the vendor's patch.

## Is CVE-2026-52921 being exploited?

There is no known exploitation of CVE-2026-52921 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-2026-52921 and fix it if it is affected.

What it is: CVE-2026-52921 is a medium-severity denial of service vulnerability in Linux kernel, published on 24 Jun 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-2026-52921 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-2026-52921/ (Markdown: https://insights.sbomify.com/CVE-2026-52921/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-52921
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-52921
- OSV: https://osv.dev/vulnerability/CVE-2026-52921

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-52921/
Summaries are generated and may contain mistakes; the official description above is the record.