CVE-2026-56862: Limit handshake messages we are willing to accept post-handshake in crypto/tls
Published Aug 13, 2026
·Updated
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.
Affected Software
1 affected component
crypto/tls
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Compensating control
Limit the number of post-handshake TLS handshake messages accepted by the server (specifically include KeyUpdate) to prevent a malicious client from forcing indefinite key derivation operations.
Event History
Aug 13, 2026
CVE Published
via MITRE·09:58 PM
Data Sourced
via MITRE·09:58 PM
DescriptionWeakness