# CVE-2026-49428: posixshm: system calls can incorrectly free memory of largepage objects

> An unprivileged local user can exploit a use-after-free bug in FreeBSD kernel system calls to access freed memory and escalate privileges.

- **Severity:** High 8.4 (`CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 19 Aug 2026
- **Updated:** 20 Aug 2026
- **Also known as:** GHSA-7m85-fgv2-gv39

## What is CVE-2026-49428?

CVE-2026-49428 is a high-severity use after free vulnerability in Freebsd Freebsd, published on 19 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

Certain system calls, such open(2) with the O_TRUNC flag set, and fspacectl(2), could incorrectly free memory in largepage objects.  These operations are not permitted on largepage objects, but the implementation did not verify this.

An unprivileged local user can abuse the bug to access freed kernel memory.  This can be exploited to escalate privileges.

Weakness: CWE-915 (Improperly Controlled Modification of Dynamically-Determined Object Attributes)

## Which versions are affected by CVE-2026-49428?

It affects 1 product.


Products: Freebsd Freebsd.

## How do I fix CVE-2026-49428?

No fix has been published for CVE-2026-49428 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-49428 being exploited?

There is no known exploitation of CVE-2026-49428 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-2026-49428 and fix it if it is affected.

What it is: CVE-2026-49428 is a high-severity use after free vulnerability in Freebsd Freebsd, published on 19 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-2026-49428 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-2026-49428/ (Markdown: https://insights.sbomify.com/CVE-2026-49428/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-49428
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-49428
- OSV: https://osv.dev/vulnerability/CVE-2026-49428

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-49428/
Summaries are generated and may contain mistakes; the official description above is the record.