What’s Vulnerable › Vulnerabilities

CVE-2026-98009: net/sched: ets: clamp quantum in parse and fallback paths

• Severity: unknown
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-09-25 · updated 2026-10-19

Description

In the Linux kernel, the following vulnerability has been resolved: net/sched: ets: clamp quantum in parse and fallback paths ets_qdisc_change() falls back to psched_mtu() with no floor for bands without an explicit quantum. With a crafted size table qdisc_pkt_len reaches ~2 GiB, so a zero psched_mtu on a headerless device makes the deficit-refill loop spin under the qdisc lock. Move the floor into ets_quantum_parse() so explicitly configured quanta are also clamped to [256, 1<<20], not just the fallback path. Conditions to recreate the bug: CONFIG_NET_SCH_ETS=y. Requires CAP_NET_ADMIN (namespace-local via unshare -Urn suffices). tc qdisc add dev dummy0 root ets bands 3 strict 2 quanta 1 1

Affected products

• Linux kernel: 5.6 — fixed in 7.3

How to fix

Upgrade to a fixed version: Linux kernel 7.3. Check the vendor advisory for mitigations.

References

• https://git.kernel.org/stable/c/1c38487f46b243bfeefec0c0c86023a3904f2214
• https://git.kernel.org/stable/c/226d2702e74a570f5bfae6115b4706da4b94e5cf
• https://git.kernel.org/stable/c/440b66cc7b56ea38e9b878ae88da91992efaa4c4
• https://git.kernel.org/stable/c/4ef8664eafafc8db68a1d52601f17dc008a223b7
• https://git.kernel.org/stable/c/8b8d782c3b96376217087767dcf662cd3d25f226
• https://git.kernel.org/stable/c/8f80b113dea0bed3c1a31a4224b72775cd9ec52d
• https://git.kernel.org/stable/c/99ae477b892e203a37985ebc56f0063e072f7f4b
• https://git.kernel.org/stable/c/de22c30ec5598aca8797f02082d2ee1358dfa3ff

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