# CVE-2026-45259: sigqueue(2) missing capability mode restriction

> A sandboxed process can bypass Capsicum restrictions to send signals to other processes, potentially causing denial of service or privilege escalation.

- **Severity:** Medium 6.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/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:** No
- **Published:** 27 Jun 2026
- **Updated:** 29 Jun 2026

## What is CVE-2026-45259?

CVE-2026-45259 is a medium-severity vulnerability in Freebsd Freebsd, published on 27 Jun 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

sigqueue(2) was marked as permitted in capability mode with the introduction of Capsicum in 2011, but the implementation of kern_sigqueue did not include a capability mode check restricting signal delivery to the calling process's own PID.

A process in capability mode can use sigqueue(2) to send signals to any process it could signal following standard Unix permissions, bypassing the Capsicum sandbox restriction.  A compromised sandboxed process could interfere with other processes, for example by sending SIGKILL or SIGSTOP.  This could be any process running as the same user, or any process, for a superuser sandboxed process.

Weakness: CWE-266 (Incorrect Privilege Assignment)

## Which versions are affected by CVE-2026-45259?

It affects 1 product.


Products: Freebsd Freebsd.

## How do I fix CVE-2026-45259?

No fix has been published for CVE-2026-45259 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-45259 being exploited?

There is no known exploitation of CVE-2026-45259 in the wild and no public exploit code.

## Other vulnerabilities in Freebsd Freebsd

- [CVE-2018-17160](https://insights.sbomify.com/CVE-2018-17160/): Memory corruption in FreeBSD (critical 10.0)
- [CVE-2014-3954](https://insights.sbomify.com/CVE-2014-3954/): Memory corruption in n/a (critical 10.0)
- [CVE-2006-4304](https://insights.sbomify.com/CVE-2006-4304/): Memory corruption in n/a (critical 10.0)
- [CVE-2006-0226](https://insights.sbomify.com/CVE-2006-0226/): Integer overflow in n/a (critical 10.0)
- [CVE-2004-0002](https://insights.sbomify.com/CVE-2004-0002/): Denial of service in n/a (critical 10.0)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-45259 and fix it if it is affected.

What it is: CVE-2026-45259 is a medium-severity vulnerability in Freebsd Freebsd, published on 27 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-2026-45259 in the wild and no public exploit code.

Affected product: Freebsd Freebsd. 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-2026-45259/ (Markdown: https://insights.sbomify.com/CVE-2026-45259/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-45259
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-45259
- OSV: https://osv.dev/vulnerability/CVE-2026-45259

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-45259/
Summaries are generated and may contain mistakes; the official description above is the record.