In the Linux kernel, the following vulnerability has been resolved:
net/sched: drr: clamp quantum in change class
drr_change_class() rejects explicit quantum==0 but falls back to psched_mtu() with no floor. With a crafted size table qdisc_pkt_len reaches ~2 GiB, so quantum=1 (or a zero psched_mtu on a headerless device) makes the deficit-refill loop spin under the qdisc lock.
Add clamp_t(u32, quantum, 256, 1<<20) after the zero reject and on the fallback path. The explicit-zero reject is preserved.
Conditions to recreate the bug: CONFIG_NET_SCH_DRR=y. Requires CAP_NET_ADMIN (namespace-local via unshare -Urn suffices).
tc qdisc add dev dummy0 root drr tc class add dev dummy0 parent 1: classid 1:1 drr quantum 1
Covered by Rapid7
| Product | Vendor Advisory | Solution File | Added | Published |
|---|---|---|---|---|
| Debian | — | Upgrade linuxUpgrade linux-6.12 | Sep 30, 2026 | Sep 25, 2026 |
| Redhat_linux | — | No solution exists | Sep 30, 2026 | Sep 25, 2026 |
Prioritise with Active Threat Intelligence
With curated Threat Intelligence, you can see which vulnerabilities truly put you at risk, prioritize what matters most, and act before attackers do.
Explore Intelligence Hub