Security Gateway stops forwarding traffic during HTTP/2 sessions

Product: Anti-Virus, Security Gateways, Threat Emulation
Version: R81.20, R82
Last Modified: 2026-05-06

Symptoms

• /var/log/messages shows these messages:

kernel:[SIM4];cpaq_cbuf_send: cpaq_cbuf_call_api_end_ex failed
kernel:[SIM4];cpaq_cbuf_send_buffer: send chunk num 0 failed
kernel:[SIM4];sim_cphwd_stats_cb: failed to create cpaq buffer

• fwk_softlock.elg file shows persistent soft lockups with these logs:

[instance_]: Received thread_blocker signal
[instance_]: [1] 0x529dd8d0 [/lib64/libpthread.so.0] (offset 0xf8d0)
[instance_]: [2] ws_http2_frame_queue_get_amount_of_bytes_by_status.constprop.1102 [/opt/CPsuite-R81.20/fw1/lib/libfw_kern_64_us_optimized_9.so] (offset 0xb87ff0)
[instance_]: [3] ws_http2_pass [/opt/CPsuite-R81.20/fw1/lib/libfw_kern_64_us_optimized_9.so] (offset 0xa3e085)
[instance_]: [4] ws_http2_handle_stream_action [/opt/CPsuite-R81.20/fw1/lib/libfw_kern_64_us_optimized_9.so] (offset 0xa43946)
[instance_]: [5] ws_connection2_read_handler

Cause

HTTP/2 frame queues can become filled with streams stuck in a hold state. This situation can cause ws_http2_frame_queue_get_amount_of_bytes_by_status to consume more resources than intended.

Solution

This problem was fixed. The fix is included in:

• Check Point R82.10
• Jumbo Hotfix Accumulator for R82 starting from Take 44
• Jumbo Hotfix Accumulator for R81.20 starting from Take 119

If you choose not to upgrade, Check Point can supply a Hotfix. Contact Check Point Support to get a Hotfix for this issue.

A Support Engineer will make sure the Hotfix is compatible with your environment before providing the Hotfix.

For faster resolution and verification, please collect CPinfo files from the Security Management Server and Security Gateways involved in the case.

Hotfix installation instructions:

Refer to sk168597 - How to install a Hotfix.

NOTE

This solution has been verified for the specific scenario, described by the combination of Product, Version and Symptoms. It may not work in other scenarios.

Article Properties

Access Level: General
Status: Approved by TAC
Date Created: 2025-09-03
Last Modified: 2026-05-06