Critical Zero-Day Exploit Targets PQC Hybrid TLS Gateways Across Fortune 500 Infrastructure

A high-severity zero-day vulnerability in hybrid post-quantum cryptography (PQC) handshake parsers is being actively exploited in the wild. The vulnerability, designated **CVE-2026-89102**, allows remote unauthenticated threat actors to crash target edge proxies and execute arbitrary code on exposed gateway hardware. According to research published by BlueCiphr Threat Labs, the vulnerability stems from an integer overflow when parsing hybrid ML-KEM-1024 payload length extensions alongside legacy RSA certificates. ### Technical Analysis & Threat Vector During the client hello phase of a hybrid TLS 1.3 handshake, the implementation fails to correctly bound the buffer allocation for post-quantum public keys when fallback RSA signatures are negotiated simultaneously. ```c // Vulnerable state check in legacy handshake buffer if (client_pqc_len + rsa_key_len > MAX_HANDSHAKE_BUF) { // Integer wrap around occurs when rsa_key_len is crafted as 0xFFFF allocate_crypto_buffer(client_pqc_len + rsa_key_len); } ``` ### Indicators of Compromise (IoCs) - **Malicious IP Ranges**: 194.26.29.11, 45.154.255.88 - **Payload Signature**: `\x90\x90\x4d\x4c\x4b\x45\x4d\x5f\x42\x59\x50\x41\x53\x53` - **Targeted Software**: Hybrid TLS Gateway v4.0.0 through v4.12.7 ### Immediate Remediation BlueCiphr recommends all SOC teams to deploy the updated CBOM scanner to inventory exposed ML-KEM crypto endpoints and apply vendor patch v4.12.8 immediately.

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