# CVE-2023-3724: TLS 1.3 client issue handling malicious server when not including a KSE and PSK extension


- **Severity:** Critical 9.1 (`CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Fix available:** Yes
- **Published:** 17 Jul 2023
- **Updated:** 29 Oct 2024
- **Also known as:** AZL-27649, DEBIAN-CVE-2023-3724, GHSA-h4rv-393v-2f5h, JLSEC-2026-676, UBUNTU-CVE-2023-3724

## What is CVE-2023-3724?

CVE-2023-3724 is a critical vulnerability in Wolfssl Wolfssl, published on 17 Jul 2023. 

### Official description

If a TLS 1.3 client gets neither a PSK (pre shared key) extension nor a KSE (key share extension) when connecting to a malicious server, a default predictable buffer gets used for the IKM (Input Keying Material) value when generating the session master secret. Using a potentially known IKM value when generating the session master secret key compromises the key generated, allowing an eavesdropper to reconstruct it and potentially allowing access to or meddling with message contents in the session. This issue does not affect client validation of connected servers, nor expose private key information, but could result in an insecure TLS 1.3 session when not controlling both sides of the connection. wolfSSL recommends that TLS 1.3 client side users update the version of wolfSSL used.

Weakness: CWE-295 (Improper Certificate Validation), CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2023-3724?

It affects 1 product.


Products: Wolfssl Wolfssl.

## How do I fix CVE-2023-3724?

Upgrade to a fixed version.

## Is CVE-2023-3724 being exploited?

There is no known exploitation of CVE-2023-3724 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-2023-3724 and fix it if it is affected.

What it is: CVE-2023-3724 is a critical vulnerability in Wolfssl Wolfssl, published on 17 Jul 2023. 
Exploitation: There is no known exploitation of CVE-2023-3724 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-2023-3724/ (Markdown: https://insights.sbomify.com/CVE-2023-3724/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-3724
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-3724
- OSV: https://osv.dev/vulnerability/CVE-2023-3724

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-3724/
Summaries are generated and may contain mistakes; the official description above is the record.