CVE-2026-90050

CVE CVE-2026-90050EUVD EUVD-2026-81911Published 2026-09-17T16:05:36.000Z

What the advisory describes

In the Linux kernel, the following vulnerability has been resolved: net/sched: fq: clamp quantum and initial_quantum in change path The fq change path accepts TCA_FQ_QUANTUM in [1, INT_MAX] and TCA_FQ_INITIAL_QUANTUM up to INT_MAX, while fq_init() already clamps to [1, 1<<20]. A user can override the init clamp via tc qdisc change, restoring the small-quantum deficit spin that the init clamp prevents. Narrow iq_range.max to 1<<20 so TCA_FQ_INITIAL_QUANTUM is rejected at parse time. Clamp TCA_FQ_QUANTUM to [256, 1<<20] in fq_change() and fq_init() quantum to [256, 1<<20] for tiny-MTU devices. Conditions to recreate the bug: CONFIG_NET_SCH_FQ=y. Requires CAP_NET_ADMIN (namespace-local via unshare -Urn suffices). tc qdisc add dev dummy0 root fq tc qdisc change dev dummy0 root fq quantum 1 stab data 32768 size_log 15 cell_log 0

Source: EUVD (ENISA), in the words of the advisory.

Products the advisory names

These come from the advisory itself, not from any check we performed.

Linux — Linux 709f34f7c28dc4dd6c40343d101850f11e172312 <094cc07f98dfe70a34e2a1923af17fd29b8cf622; e35acd56f244d94355f9ab237c2ecc8fba5e6f04 <72e9387884554f47b03bfd40fb8b2bf52789c68d; patch: 7.3-rc3; 7.3-rc1; f6b3e3848a5fca63438984acd6d9eceac80814c1 <798283cd0fe7ba997f67e5a917f14ab40afa8d9f; d16dac3925be95ad46e986d4b139c9898b6e227f <a27498d34c3f429fb6db3aa609569f8154afa175; patch: 0

The versions shown are the advisory's own. Patchlage compares no version numbers and derives no judgement from them — which version is installed is something a person has to look up.

Carried in the product catalogue

An estate covering these products can be recorded in Patchlage. An advisory about them appears in the next morning's situation report.

Linux — Linux

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