# CVE-2026-5772: MatchDomainName 1-Byte Stack Buffer Over-Read in Hostname Validation

> A 1-byte stack buffer over-read in wolfSSL's hostname validation can cause a crash when the LEFT_MOST_WILDCARD_ONLY flag is active.

- **Severity:** Low 2.1 (`CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:P/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 9 Apr 2026
- **Updated:** 10 Apr 2026
- **Also known as:** DEBIAN-CVE-2026-5772, GHSA-6v2v-jgg9-h79w, JLSEC-2026-740, UBUNTU-CVE-2026-5772

## What is CVE-2026-5772?

CVE-2026-5772 is a low-severity memory corruption vulnerability in Wolfssl Wolfssl, published on 9 Apr 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.

### Official description

A 1-byte stack buffer over-read was identified in the MatchDomainName function (src/internal.c) during wildcard hostname validation when the LEFT_MOST_WILDCARD_ONLY flag is active.  If a wildcard * exhausts the entire hostname string, the function reads one byte past the buffer without a bounds check, which could cause a crash.

Weakness: CWE-126 (Buffer Over-read)

## Which versions are affected by CVE-2026-5772?

It affects 1 product.


Products: Wolfssl Wolfssl.

## How do I fix CVE-2026-5772?

Apply the vendor's patch.

## Is CVE-2026-5772 being exploited?

There is no known exploitation of CVE-2026-5772 in the wild and no public exploit code.

## Other vulnerabilities in Wolfssl Wolfssl

- [CVE-2024-5991](https://insights.sbomify.com/CVE-2024-5991/): Buffer overread in domain name matching (critical 10.0)
- [CVE-2021-37155](https://insights.sbomify.com/CVE-2021-37155/): Security feature bypass in n/a (critical 9.8)
- [CVE-2020-36177](https://insights.sbomify.com/CVE-2020-36177/): Memory corruption in n/a (critical 9.8)
- [CVE-2014-2896](https://insights.sbomify.com/CVE-2014-2896/): Memory corruption in n/a (critical 9.8)
- [CVE-2014-2897](https://insights.sbomify.com/CVE-2014-2897/): Memory corruption in n/a (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-5772 and fix it if it is affected.

What it is: CVE-2026-5772 is a low-severity memory corruption vulnerability in Wolfssl Wolfssl, published on 9 Apr 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-5772 in the wild and no public exploit code.

Affected product: Wolfssl Wolfssl. 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-2026-5772/ (Markdown: https://insights.sbomify.com/CVE-2026-5772/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-5772
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-5772
- OSV: https://osv.dev/vulnerability/CVE-2026-5772

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-5772/
Summaries are generated and may contain mistakes; the official description above is the record.