Bug ID 1937777: The client can resume a TLS session using psk_ke mode in the psk_key_exchange_modes extension.

Last Modified: Sep 01, 2025

Affected Product(s):
BIG-IP All(all modules)

Known Affected Versions:
17.5.0, 17.5.1

Opened: May 14, 2025

Severity: 3-Major

Symptoms

In TLS, the psk_key_exchange_modes extension in the Client Hello specifies the supported key exchange modes for resuming sessions with pre-shared keys (PSK). As per Common Criteria guidelines, if client hello contains only psk_ke mode in the "psk_key_exchange_modes" extension then TLS handshake either (1) implicitly rejects the session ticket by performing a full handshake, or (2) terminates the TLS handshake to prevent the flow of application data.

Impact

TLS handshake will be successful with this configuration.

Conditions

In ClientHello, only psk_ke mode should be present in the "psk_key_exchange_modes" extension. ClientHello should contain "pre_shared_key" extension too.

Workaround

None

Fix Information

None

Behavior Change

Guides & references

K10134038: F5 Bug Tracker Filter Names and Tips