CVE-2026-90072
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Vulnerability report for CVE-2026-90072, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.
Publication date: 2026-09-17
Last updated on: 2026-09-17
Assigner: kernel.org
Description
Description
In the Linux kernel, the following vulnerability has been resolved:
net/sched: sfq: clamp quantum to avoid signed overflow soft lockup
sfq_init() sets q->quantum = psched_mtu(qdisc_dev(sch)) (unsigned). A
device with a huge MTU (e.g. dummy with max_mtu == 0 accepting MTU
2147483634) makes psched_mtu() return 0x80000000, so slot->allot = INT_MIN
and INT_MIN + INT_MIN toggles between INT_MIN and 0 forever, spinning
sfq_dequeue() under the qdisc lock.
Clamp the quantum to [256, 1 << 20] so the refill loop terminates. The
lower bound also covers q->quantum == 0 (psched_mtu() returning 0),
which spins sfq_dequeue() identically. sfq_change() already rejects a
negative quantum, so only the init path was exposed.
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 Scores
EPSS Scores
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Meta Information
Affected Vendors & Products
Currently, no data is known.
Helpful Resources
Exploitability
CWE
KEV
| CWE ID | Description |
|---|---|
| CWE-UNKNOWN |
