What’s Vulnerable › Vulnerabilities

CVE-2026-98010: net/sched: drr: clamp quantum in change class

• 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: 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

Affected products

• Linux kernel: 2.6.29 — 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/23fea7e6736b2e1c6f6f2f05cccf33d36834da73
• https://git.kernel.org/stable/c/560794ee6e040b6e1c4ac2b3c8909f341a4596ee
• https://git.kernel.org/stable/c/8382abec0f1568d0a5590d75a3df92f23fcf5196
• https://git.kernel.org/stable/c/8f756ae1c87414ce9cc21b30e6e4c036d6e9e80b
• https://git.kernel.org/stable/c/b464affe9f9dfe41ac48930c376e3fb8596651b0
• https://git.kernel.org/stable/c/d43cded350fe1218493ad3d37a276aff14108ae6
• https://git.kernel.org/stable/c/dc8b374214ef5bba4882bbd95b361e42555cfc0d
• https://git.kernel.org/stable/c/e2297bbf9cf6ece86f1d1f8c683517a994990f9e

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