# CVE-2026-81020: wolfEngine reuses the AES-GCM nonce on every TLS 1.2 / DTLS 1.2 record


- **Severity:** High 7.4 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Fix available:** No
- **Published:** 28 Aug 2026
- **Updated:** 28 Aug 2026
- **Also known as:** GHSA-8x67-443h-6cwx

## What is CVE-2026-81020?

CVE-2026-81020 is a high-severity vulnerability in wolfSSL Inc. wolfEngine, published on 28 Aug 2026. 

### Official description

wolfEngine before 1.4.1 generates the 8-byte explicit AES-GCM nonce once when the TLS write key is set and never increments it per record. As a result every TLS 1.2 and DTLS 1.2 AES-GCM record within a connection is encrypted under an identical key and nonce pair. Reusing a GCM key and nonce discloses the keystream (the XOR of two ciphertexts equals the XOR of their plaintexts, so one known record recovers the others) and leaks the GHASH authentication key, enabling authentication tag forgery. AES-CCM, TLS 1.3, and non-TLS use of the cipher are not affected.

Weakness: CWE-323 (Reusing a Nonce, Key Pair in Encryption)

## Which versions are affected by CVE-2026-81020?

It affects 1 product.


Products: Wolfssl Wolfengine.

## How do I fix CVE-2026-81020?

No fix has been published for CVE-2026-81020 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-81020 being exploited?

There is no known exploitation of CVE-2026-81020 in the wild and no public exploit code.

## Other vulnerabilities in wolfSSL Inc. wolfEngine

- [CVE-2026-81341](https://insights.sbomify.com/CVE-2026-81341/): wolfEngine reuses the AES-CCM nonce on TLS 1.2 / DTLS 1.2 records (medium 6.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-81020 and fix it if it is affected.

What it is: CVE-2026-81020 is a high-severity vulnerability in wolfSSL Inc. wolfEngine, published on 28 Aug 2026. 
Exploitation: There is no known exploitation of CVE-2026-81020 in the wild and no public exploit code.

Affected product: wolfSSL Inc. wolfEngine. 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-2026-81020/ (Markdown: https://insights.sbomify.com/CVE-2026-81020/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-81020
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-81020
- OSV: https://osv.dev/vulnerability/CVE-2026-81020

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-81020/
Summaries are generated and may contain mistakes; the official description above is the record.