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CVE-2026-90050— net/sched: fq: clamp quantum and initial_quantum in change path

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

在 Linux 内核中，已修复以下漏洞： net/sched: fq: 在变更路径中限制（clamp）quantum 和 initial_quantum fq 的变更路径接受 TCA_FQ_QUANTUM 在 [1, INT_MAX] 范围内，以及 TCA_FQ_INITIAL_QUANTUM 最大可达 INT_MAX，而 已经将其限制在 [1, 1<<20]。用户可通过 覆盖初始化的限制，从而重新引发因极小 quantum 导致的性能缺陷（deficit spin），而该缺陷本应被初始化时的限制所规避。 修复措施

AI Predicted 5.5 Difficulty: Easy EPSS 0.21% · P10

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application

Affected Version Matrix 7

VendorProduct Version RangeStatus
Linux Linux d16dac3925be95ad46e986d4b139c9898b6e227f< a27498d34c3f429fb6db3aa609569f8154afa175 affected
f6b3e3848a5fca63438984acd6d9eceac80814c1< 798283cd0fe7ba997f67e5a917f14ab40afa8d9f affected
e35acd56f244d94355f9ab237c2ecc8fba5e6f04< 72e9387884554f47b03bfd40fb8b2bf52789c68d affected
709f34f7c28dc4dd6c40343d101850f11e172312< 094cc07f98dfe70a34e2a1923af17fd29b8cf622 affected
7.3-rc1 affected
< 7.3-rc1 unaffected
7.3-rc3≤ * unaffected
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I. Basic Information for CVE-2026-90050

Vulnerability Information
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Vulnerability Title
net/sched: fq: clamp quantum and initial_quantum in change path
Source: CVE Program / CVE List V5
Vulnerability Description
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: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux d16dac3925be95ad46e986d4b139c9898b6e227f ~ a27498d34c3f429fb6db3aa609569f8154afa175 -
Linux Linux 7.3-rc1 -

II. Public POCs for CVE-2026-90050

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III. Intelligence Information for CVE-2026-90050

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Patches & Fixes for CVE-2026-90050 (4)

Same Patch Batch · Linux · 2026-09-17 · 600 CVEs total

CVE-2026-90173 9.8 CRITICAL smb: smbdirect: free completion queues with ib_free_cq()
CVE-2026-92489 9.8 CRITICAL xfrm: Fix skb double-free in xfrm_dev_direct_output()
CVE-2026-90104 9.8 CRITICAL NFSv4.1: zero referring call lists before decoding
CVE-2026-90235 9.8 CRITICAL sunrpc: xprtsock: annotate shared socket callbacks with READ_ONCE/WRITE_ONCE
CVE-2026-90151 9.8 CRITICAL NFSv4: remove callback IDR entry on client allocation failure
CVE-2026-90110 9.4 CRITICAL inetpeer: randomize RB-tree node comparison using SipHash
CVE-2026-90414 9.1 CRITICAL IB/isert: reject PDUs declaring more data than was received
CVE-2026-90413 9.1 CRITICAL IB/isert: reject login PDUs declaring more data than was received
CVE-2026-90230 9.1 CRITICAL nvmet: fix heap out-of-bounds read in nvmet_auth_negotiate()
CVE-2026-90380 8.8 HIGH wifi: mt76: mt792x: fix use-after-free in mt76_rx_poll_complete
CVE-2026-90329 8.8 HIGH HID: synchronize input before cleaning up a failed probe
CVE-2026-90162 8.8 HIGH ksmbd: defer publishing granted locks to prevent UAF/double-free race
CVE-2026-90357 8.8 HIGH wifi: mt76: mt7915: unlink TWT flow if the MCU rejects the agreement
CVE-2026-90367 8.8 HIGH wifi: mt76: mt7996: hold dev->mt76.mutex while disabling tx worker in SER
CVE-2026-90381 8.8 HIGH wifi: mt76: fix handling channel context with different bands in mt76_switch_vif_chanctx()
CVE-2026-90425 8.8 HIGH iommu/tegra241-cmdqv: Require exactly one Stream ID for a vSID
CVE-2026-90240 8.8 HIGH iommu/vt-d: Flush context cache with correct SID when tearing down aliases
CVE-2026-90379 8.8 HIGH wifi: mt76: mt7921: Add PCIe AER handler support to prevent system crash
CVE-2026-93042 8.8 HIGH dmaengine: dw-edma: Terminate all descriptors without callbacks
CVE-2026-90371 8.8 HIGH wifi: mt76: fix RXDMAD_C buffer recycling race

Showing top 20 of 600 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

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