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CVE-2026-98427— net/sched: codel: bound the dropping loop per dequeue call

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.

In the Linux kernel, the following vulnerability has been resolved: net/sched: codel: bound the dropping loop per dequeue call The CoDel control law schedules the next drop one interval/sqrt(count) after the previous drop, using the configured interval (codel_

Affected Version Matrix 6

VendorProduct Version RangeStatus
Linux Linux 76e3cc126bb223013a6b9a0e2a51238d1ef2e409< bacd72289d34d8c05b7de5a12448b87b6dd93878 affected
76e3cc126bb223013a6b9a0e2a51238d1ef2e409< 7f4a5ec6258fd7c92633ec4b0493fc51166d9398 affected
3.5 affected
< 3.5 unaffected
7.2.8≤ 7.2.* unaffected
7.3-rc4≤ * unaffected
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I. Basic Information for CVE-2026-98427

Vulnerability Information

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Vulnerability Title
net/sched: codel: bound the dropping loop per dequeue call
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: net/sched: codel: bound the dropping loop per dequeue call The CoDel control law schedules the next drop one interval/sqrt(count) after the previous drop, using the configured interval (codel_params.interval). For very small intervals the scheduled step rounds down to zero, so the dropping loop in codel_dequeue() never advances and drains the entire backlog under the qdisc lock in one call - an unprivileged user can trigger a soft lockup this way. Fix in the shared codel code used by both codel and fq_codel: 1. Make the control-law step at least 1 tick so the dropping loop always moves forward. 2. Cap the dropping loop at CODEL_MAX_DROPS_PER_DEQUEUE (256) drops per codel_dequeue() call, resyncing drop_next to now when the cap is hit: the catch-up owed to the loop grows with the idle gap and the backlog, which no interval threshold can bound. This is a deliberate behaviour change after long idle gaps. The cap applies to fq_codel (4b549a2ef4be) and the mac80211 TXQ path (fixed interval, cap only). The target sojourn delay (codel_params.target) is not validated: it does not feed the control law, so a sub-tick value is aggressive rather than deadlock-prone. Conditions to recreate the bug: - tc qdisc add dev lo root handle 1: tbf rate 1kbit burst 2kb limit 1000000 - tc qdisc add dev lo parent 1:1 handle 10: codel interval 2us target 1ms noecn limit 1000000 (same for fq_codel) - unpatched kernel: tc accepts it; a UDP flood under the 1kbit tbf soft-lockups (watchdog: BUG: soft lockup) while one codel_dequeue() call drops the backlog under the qdisc lock - patched kernel: same setup, at most 256 drops per dequeue call, no soft lockup Testing: claim reproducer and interval 2us/3us variants run clean; tdc qdisc category passes (see the selftests patch).
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 76e3cc126bb223013a6b9a0e2a51238d1ef2e409 ~ bacd72289d34d8c05b7de5a12448b87b6dd93878 -
Linux Linux 3.5 -

II. Public POCs for CVE-2026-98427

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III. Intelligence Information for CVE-2026-98427

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Other References for CVE-2026-98427 (2)

Same Patch Batch · Linux · 2026-10-14 · 46 CVEs total

CVE-2026-98398 locking/lockdep: Invalidate stale class_cache entries for zapped classes
CVE-2026-98396 powerpc: Do not restore KUAP in arch_exit_to_user_mode_prepare()
CVE-2026-98393 net: ipv4: Fix UDP length overflow with PMTU discover and big MTU
CVE-2026-98391 drm/xe: Guard page-fault worker with runtime PM check
CVE-2026-98389 drm/amdgpu: skip gfx switch_power_profile during GPU reset
CVE-2026-98388 exec: do_close_on_exec() before taking exec_update_lock
CVE-2026-98387 s390/crypto: Fix skcipher_walk return code handling in aes_s390
CVE-2026-98386 scsi: qla2xxx: Use memset_io() to clear QLAFX00 request ring slot
CVE-2026-98390 x86/amd_node: Avoid divide by zero on virtualized systems
CVE-2026-98397 platform/x86: x86-android-tablets: hold device reference for secondary fwnode teardown
CVE-2026-98395 powerpc/entry: Fix irq_soft_mask corruption on replayed interrupt exit
CVE-2026-98399 s390/ipl: Fix NULL deref in dump_reipl without re-IPL parm block
CVE-2026-98400 s390/ipl: Fix NULL deref in kdump without re-IPL parm block
CVE-2026-98402 net: icmp: avoid invalid transport header access in icmp_send tracepoint
CVE-2026-98401 net: iptunnel: fix stale transport header during tunnel decapsulation
CVE-2026-98403 s390/boot: Avoid IPL parameter append past command line
CVE-2026-98404 drm/virtio: Fix a NULL vs ERR_PTR() bug in virtio_gpu_user_framebuffer_create()
CVE-2026-98405 smb: client: fix missing iov bounds check in parse_posix_sids()
CVE-2026-98406 wifi: mac80211: avoid WARN in set_bitrate_mask when sdata not in driver
CVE-2026-98408 watchdog: rzv2h: Avoid division by zero

Showing top 20 of 46 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-98427

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