CVE-2026-81020
CVE-2026-81020 is a high-severity vulnerability in Wolfssl Wolfengine with a CVSS 3.x base score of 7.4. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-323.
Key facts
- Severity: High (CVSS 3.x base score 7.4)
- EPSS exploit prediction: 0% (30th percentile)
- Actively exploited: Not listed in CISA KEV
- Weakness: CWE-323
- Affected product: Wolfssl Wolfengine
- Published:
- Last modified:
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.
Frequently asked questions
- What is CVE-2026-81020?
- 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.
- How severe is CVE-2026-81020?
- CVE-2026-81020 has a CVSS 3.x base score of 7.4, rated high severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability none.
- Is CVE-2026-81020 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (30th percentile), an estimate of the probability of exploitation in the next 30 days.
- What products are affected by CVE-2026-81020?
- CVE-2026-81020 affects Wolfssl Wolfengine. See the affected-products list for the exact vulnerable versions.
- How do I fix CVE-2026-81020?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
- When was CVE-2026-81020 published?
- CVE-2026-81020 was published on 2026-08-28 and last updated on 2026-09-29.
References
Affected products (1)
- cpe:2.3:a:wolfssl:wolfengine:*:*:*:*:*:*:*:*
More vulnerabilities in Wolfssl Wolfengine
- CVE-2026-81341 — Medium (CVSS 6.5): wolfEngine before 1.4.1 sources the explicit AES-CCM nonce for TLS 1.2 and DTLS 1.2 records from the record input…
All CVEs affecting Wolfssl Wolfengine →
Other CWE-323 vulnerabilities
- CVE-2026-59099 — Critical (CVSS 9.1): Apereo CAS 7.3.0 before 8.0.0-RC6 contains a cryptographic vulnerability that allows remote unauthenticated attackers…
- CVE-2026-12205 — Critical (CVSS 9.1): Crypt::DSA versions before 1.21 for Perl reused the nonce across signatures, leading to private-key…
- CVE-2026-49952 — Critical (CVSS 9.1): Discuz! X5.0 releases 20260320 through 20260501 contains an authentication bypass vulnerability that allows…
- CVE-2025-64767 — Critical (CVSS 9.1): hpke-js is a Hybrid Public Key Encryption (HPKE) module built on top of Web Cryptography API. Prior to version 1.7.5,…
- CVE-2025-47345 — High (CVSS 8.4): Cryptographic issue may occur while encrypting license data.
- CVE-2026-3559 — High (CVSS 8.1): Philips Hue Bridge HomeKit Accessory Protocol Static Nonce Authentication Bypass Vulnerability. This vulnerability…