# CVE-2026-49423: Remote DOS via uninitialized memory access in KTLS receive

> A remote attacker can cause a kernel panic in FreeBSD by triggering uninitialized memory access during TLS record processing.

- **Severity:** Low 3.3 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N`)
- **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:** 19 Aug 2026
- **Updated:** 26 Aug 2026
- **Also known as:** GHSA-c5hg-f3pf-qgxh

## What is CVE-2026-49423?

CVE-2026-49423 is a low-severity 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

When building the iovec array for a received TLS 1.2 CBC record, ktls_ocf_tls_cbc_decrypt() incremented the iovec index for every mbuf in the chain, including mbufs that were skipped because they contained only TLS header bytes.  This left uninitialized entries in the iovec array.  The iovec array was allocated without zeroing.

A remote TLS peer can cause the kernel to read from uninitialized iovec entries during HMAC computation, resulting in a kernel panic.  The peer must be able to control TCP segmentation such that the first mbuf of a CBC record contains only the 5-byte TLS record header.

Weakness: CWE-908 (Use of Uninitialized Resource)

## Which versions are affected by CVE-2026-49423?

It affects 1 product.


Products: Freebsd Freebsd.

## How do I fix CVE-2026-49423?

No fix has been published for CVE-2026-49423 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-49423 being exploited?

There is no known exploitation of CVE-2026-49423 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-2026-49423 and fix it if it is affected.

What it is: CVE-2026-49423 is a low-severity 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-2026-49423 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-2026-49423/ (Markdown: https://insights.sbomify.com/CVE-2026-49423/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-49423
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-49423
- OSV: https://osv.dev/vulnerability/CVE-2026-49423

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-49423/
Summaries are generated and may contain mistakes; the official description above is the record.