CVE-2026-56862
HighCVSS 7.5Exploitation Probability (EPSS)
Low risk8th percentile - higher than 8% of all known CVEs
Summary
Handshake messages, such as KeyUpdate, are always considered as state-advancing, regardless of whether a handshake has been completed or not. As a result, a malicious client can keep sending KeyUpdate messages to force the server to keep performing key derivation operations indefinitely.
Risk Assessment
An attacker could cause server overload, leading to denial of service (DoS) and resource exhaustion.
Recommendation
Apply patches provided by the software vendor that limit processing of KeyUpdate messages after handshake completion.
Original NVD description (English source)
Handshake messages, such as KeyUpdate, are always considered as state-advancing, regardless of whether a handshake has been completed or not. As a result, a malicious client can keep sending KeyUpdate messages to force the server to keep performing key derivation operations indefinitely.