# CVE-2026-58098: Heap out-of-bounds access in semop(2)

> An unprivileged local user can trigger a heap out-of-bounds access in the FreeBSD kernel via semop(2), potentially leading to privilege escalation.

- **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:** 15 Oct 2026
- **Updated:** 16 Oct 2026

## What is CVE-2026-58098?

CVE-2026-58098 is a high-severity memory corruption vulnerability in Freebsd Freebsd, published on 15 Oct 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

When semop(2) blocks waiting for a semaphore condition, it releases the per-set lock and sleeps.  Upon waking, it checks the sequence number embedded in the semaphore set's IPC identifier to detect whether the set was removed while the caller was asleep.  This sequence number is only 15 bits wide.  If enough semaphore sets are created and destroyed in the same table slot while a caller is blocked, the counter wraps around, and semop(2) may falsely conclude that the original set still exists.  The subsequent access to a semaphore within the set may then be out of bounds.

An unprivileged local user can trigger an out-of-bounds access on kernel heap memory, potentially leading to privilege escalation.

Weakness: CWE-787 (Out-of-bounds Write)

## Which versions are affected by CVE-2026-58098?

It affects 1 product.


Products: Freebsd Freebsd.

## How do I fix CVE-2026-58098?

No fix has been published for CVE-2026-58098 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-58098 being exploited?

There is no known exploitation of CVE-2026-58098 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-2026-58098 and fix it if it is affected.

What it is: CVE-2026-58098 is a high-severity memory corruption vulnerability in Freebsd Freebsd, published on 15 Oct 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-2026-58098 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-2026-58098/ (Markdown: https://insights.sbomify.com/CVE-2026-58098/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-58098
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-58098
- OSV: https://osv.dev/vulnerability/CVE-2026-58098

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-58098/
Summaries are generated and may contain mistakes; the official description above is the record.