CVE-2026-90073net/sched: hhf: clamp quantum before hhf_change() to avoid overflow
Updated under an hour ago ()
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No exploitation reported and no EPSS estimate yet.
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In the Linux kernel, the following vulnerability has been resolved: net/sched: hhf: clamp quantum before hhf_change() to avoid overflow hhf_init() sets q->quantum = psched_mtu(qdisc_dev(sch)) with no overflow check. A device with a huge MTU (e.g. dummy with max_mtu == 0 accepting MTU 2147483634) makes weight * quantum overflow the signed deficit in hhf_dequeue(), spinning forever. Clamp q->quantum before hhf_change() so both the opt and !opt paths see a sane quantum. Without this, bare "tc qdisc add ... hhf" succeeds with a clamped quantum but "tc qdisc add ... hhf limit 1000" (any option present) fails with -EINVAL because hhf_change() re-validates the unclamped default (sch_hhf.c:559). 256 matches fq_codel's floor and is a sane minimum for a DRR quantum. Conditions to recreate the bug: a device whose MTU (plus hard_header_len) wraps psched_mtu() into the sign bit (e.g. a dummy device with max_mtu == 0 accepting MTU 2147483634). Requires CAP_NET_ADMIN in a user namespace.
- CVSS
- Not yet scored
- Weakness (CWE)
- Not given
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- Linux
- NVD analysis
- Received
- Record last updated
- Oct 19, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
Linux Linux linux:linux (from the name) | 10239edf86f137ce4c39b62ea9575e8053c549a0 builds before 2e0f0729f922c8de13801004e2131b57646c7c5f; 10239edf86f137ce4c39b62ea9575e8053c549a0 builds before 0c66223e90ddb4fd3700965a9241f2fde7bd6bc7; 10239edf86f137ce4c39b62ea9575e8053c549a0 builds before 20b65bf7ca06e48ec1d62ed8012f71205328dbe4; from 10239edf86f137ce4c39b62ea9575e8053c549a0 before dea2789a9d5ff38bdd77f2e64d550430899e2839; from 10239edf86f137ce4c39b62ea9575e8053c549a0 before fa9c2055f0a60f801ccf286af53d387dc6202c3f; from 10239edf86f137ce4c39b62ea9575e8053c549a0 before 99770b5d8e0e1c69b996f74a19d71afd2c4a9aa4; from 10239edf86f137ce4c39b62ea9575e8053c549a0 before 2446644b0f6d045b01db6acbaf55552dbec8a59a; 10239edf86f137ce4c39b62ea9575e8053c549a0 builds before 2164b512b97bb053e8ce4d6e95576f11bed6a005 | CNA record |
References
- https://git.kernel.org/stable/c/2e0f0729f922c8de13801004e2131b57646c7c5f
- https://git.kernel.org/stable/c/0c66223e90ddb4fd3700965a9241f2fde7bd6bc7
- https://git.kernel.org/stable/c/20b65bf7ca06e48ec1d62ed8012f71205328dbe4
- https://git.kernel.org/stable/c/dea2789a9d5ff38bdd77f2e64d550430899e2839
- https://git.kernel.org/stable/c/fa9c2055f0a60f801ccf286af53d387dc6202c3f
- https://git.kernel.org/stable/c/99770b5d8e0e1c69b996f74a19d71afd2c4a9aa4
- https://git.kernel.org/stable/c/2446644b0f6d045b01db6acbaf55552dbec8a59a
- https://git.kernel.org/stable/c/2164b512b97bb053e8ce4d6e95576f11bed6a005
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.