CVE-2026-81020

wolfEngine reuses the AES-GCM nonce on every TLS 1.2 / DTLS 1.2 record

Published Aug 28, 2026 CVSS 3.1 · 7.4 High EPSS < 1% KEV · Not listed
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.

Remediation

Vendor Solution

Upgrade to wolfEngine 1.4.1, which increments the explicit nonce after each record. As an interim mitigation use AES-CCM or TLS 1.3 instead of TLS 1.2 / DTLS 1.2 AES-GCM.

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}

Type Values Removed Values Added
CPEs cpe:2.3:a:wolfssl:wolfengine:*:*:*:*:*:*:*:*
Type Values Removed Values Added
First Time appeared Wolfssl
Wolfssl wolfengine
Vendors & Products Wolfssl
Wolfssl wolfengine
Type Values Removed Values Added
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.
Title wolfEngine reuses the AES-GCM nonce on every TLS 1.2 / DTLS 1.2 record
Weaknesses CWE-323
References
Metrics cvssV3_1

{'score': 7.4, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
wolfSSL
Published
Updated
Aug 28, 2026, 6:19 PM
Reserved
Aug 26, 2026, 2:40 PM
Status
Analyzed
Published
Aug 28, 2026, 4:18 PM
Modified
Sep 29, 2026, 7:10 PM