Quick answers
- Is CVE-2026-81020 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-81020 being exploited in the wild.
- How severe is CVE-2026-81020?
- High severity, with a CVSS score of 7.4, published 28 August 2026.
- Which products and versions are affected?
- Wolfssl wolfEngine before 1.4.1.
- Is there a fix for CVE-2026-81020?
- No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
- How is CVE-2026-81020 attacked?
- It is attacked over the network.
- Am I affected by CVE-2026-81020?
- Check whether you run Wolfssl wolfEngine at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
Technical details
The vulnerability is a cryptographic nonce reuse flaw in wolfEngine's TLS 1.2 and DTLS 1.2 AES-GCM implementation. The 8-byte explicit nonce is generated once when the TLS write key is set but never incremented per record, violating GCM security requirements. This allows attackers to recover the keystream (XOR of ciphertexts reveals XOR of plaintexts with one known record) and extract the GHASH authentication key for tag forgery. The flaw is present in versions before 1.4.1. TLS 1.3, AES-CCM, and non-TLS cipher usage are unaffected. Patches are available in wolfEngine 1.4.1 and later.
Affected products
- wolfSSL wolfEngine before 1.4.1
Timeline
- 2026-08-28: disclosed