CVE-2026-98234.

Disclosure summary

In the Linux kernel, the following vulnerability has been resolved: net/sched: hhf: cap hh_flows_limit at change time hhf_change() stores TCA_HHF_HH_FLOWS_LIMIT with no upper bound. A huge hh_flows_limit lets each new heavy-hitter flow pass the hh_flows_current_cnt check in alloc_new_hh() and forces a fixed-size kzalloc(GFP_ATOMIC) per flow under spoofed traffic, for unbounded memory growth. Bound the attribute with NLA_POLICY_MAX() at 2*HH_FLOWS_CNT (the hhf_init() default) and report the rejected value via extack. The deprecated nested parse is kept: legacy tc does not set NLA_F_NESTED on TCA_OPTIONS. Configs relying on hh_limit above the default were relying on unbounded, unsafe behaviour and are not supported going forward. hhf_init() also ran hhf_change() before setting the default hh_flows_limit, so a user-supplied hh_limit at add time was clobbered back to 2048. Set the default before hhf_change() so the configured value sticks. This is a follow-up to commit eb56a495f59b ("net/sched: hhf: clamp quantum in change and init paths"), which bounded the quantum of the same qdisc; the hh_flows_limit bound is the remaining unbounded knob of that series' scope. Conditions to recreate the bug: CAP_NET_ADMIN in a user namespace; tc qdisc change dev X root hhf hh_limit 4294967295 succeeds and the value is echoed by tc qdisc show, unbounding heavy-hitter flow allocations; also tc qdisc add dev X root hhf hh_limit 500 stores 2048 instead of 500.

Source-specific records & product guidance

Sources retain their own attribution and scoring. Follow the original record to confirm affected versions, fixed releases, and configuration conditions.

Original records & references

• NIST NVD record
• CVE Program record
• git.kernel.org
• git.kernel.org
• git.kernel.org
• git.kernel.org
• git.kernel.org
• git.kernel.org
• git.kernel.org
• git.kernel.org

PUBLISHED 2026-10-06T05:18:11-04:00
MODIFIED 2026-10-06T05:18:11-04:00
INGESTED 2026-10-06T11:45:53-04:00