VulnerabilityPublished 25 Sep 2026Updated 19 Oct 2026

CVE-2026-98011: Linux kernel · net/sched: hhf: clamp quantum in change and init paths

Affects Linux kernelSource CVE Database V5

Not known to be exploited · fixed in eb56a495f59baf6cad5ed80e3ffb9078098b1346 : patch Linux kernel soon.

Data as of 26 Oct 2026, 13:47 UTC

Severity

High

Rated High by Threat Radar's AI analysis · CVSS not yet scored by NVD

EPSS: 0.1% chance of exploitation in 30 days – higher than 7% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in eb56a495f59baf6cad5ed80e3ffb9078098b1346, c364ad3ab3c8a6bce469a5cbf02881ab1324c5da, a328698d046098e6f55b3b1460cac6bab577be58 +5

Exploitation evidence

Disclosed: evidence found.
CVE published 25 Sep 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ 10239edf86f137ce4c39b62ea9575e8053c549a0, < eb56a495f59baf6cad5ed80e3ffb9078098b1346	Fixed in eb56a495f59baf6cad5ed80e3ffb9078098b1346
LinuxLinux	Affected ≥ 10239edf86f137ce4c39b62ea9575e8053c549a0, < c364ad3ab3c8a6bce469a5cbf02881ab1324c5da	Fixed in c364ad3ab3c8a6bce469a5cbf02881ab1324c5da
LinuxLinux	Affected ≥ 10239edf86f137ce4c39b62ea9575e8053c549a0, < a328698d046098e6f55b3b1460cac6bab577be58	Fixed in a328698d046098e6f55b3b1460cac6bab577be58
LinuxLinux	Affected ≥ 10239edf86f137ce4c39b62ea9575e8053c549a0, < 6570f326a6a96bedf3d1d1dab6acc9f8c29104ec	Fixed in 6570f326a6a96bedf3d1d1dab6acc9f8c29104ec
LinuxLinux	Affected ≥ 10239edf86f137ce4c39b62ea9575e8053c549a0, < 1113b674307ffddd402524bd1fd9d7d5629b705b	Fixed in 1113b674307ffddd402524bd1fd9d7d5629b705b
LinuxLinux	Affected ≥ 10239edf86f137ce4c39b62ea9575e8053c549a0, < 0898c6f9fa9ce2632ae88bd0f34a878ccc6335af	Fixed in 0898c6f9fa9ce2632ae88bd0f34a878ccc6335af

AI-suggested

A fix is available and has been applied in multiple Linux kernel commits. Users should update to a fixed kernel version that includes the patches identified by the fixed commit hashes. No additional mitigation is required once the kernel is updated.

Description

CVE-2026-98011 is a vulnerability in the Linux kernel's net/sched subsystem affecting the hhf queuing discipline. The flaw allows userspace to specify a quantum value as low as 1, which can cause the deficit-refill loop to spin excessively under the qdisc lock, leading to a soft lockup and denial of service. The issue is fixed by clamping the quantum value to a minimum of 256 in the change and init paths.

Impact

An attacker with CAP_NET_ADMIN capability can trigger a denial of service by causing a soft lockup in the kernel's networking scheduler. This results in the system becoming unresponsive due to the excessive spinning of the deficit-refill loop under the qdisc lock.

Summary

The Linux kernel's hhf_change() function previously accepted any quantum value from userspace, including 1. When combined with a crafted size table, this could cause the qdisc_pkt_len to reach approximately 2 GiB, making the deficit-refill loop spin about 2^31 times under the qdisc lock. This results in a soft lockup and denial of service. The fix clamps the quantum value to at least 256 in hhf_change() and restricts hhf_init() to a range between 256 and 1<<20, aligning with sibling qdisc implementations and removing the old fallback behavior.

References

Community reviews

Loading reviews…

Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 26 Oct 2026, 13:06 UTC

Technical details

References

Community reviews

Related threats