VulnerabilityPublished 18 Oct 2026

CVE-2026-98610: Linux kernel · net/sched: sch_hfsc: bound the classify inner-filter walk with a drift budget

Affects Linux kernelSource CVE Database V5

Not known to be exploited · fixed in f476fb656ca2326d7b2eba98d03ced1cbcf5cd99 : patch Linux kernel soon.

Data as of 26 Oct 2026, 17:16 UTC

Severity

High

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

EPSS: 0.2% chance of exploitation in 30 days – higher than 11% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in f476fb656ca2326d7b2eba98d03ced1cbcf5cd99, e8f9979286f70dfbfe0552e2a63000950841bea6, d4fd251e3311727c32af89344d3332f788c153a2 +5

Exploitation evidence

Disclosed: evidence found.
CVE published 18 Oct 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 ≥ a2f79227138c71e08627af5f8961197364edbc98, < f476fb656ca2326d7b2eba98d03ced1cbcf5cd99	Fixed in f476fb656ca2326d7b2eba98d03ced1cbcf5cd99
LinuxLinux	Affected ≥ a2f79227138c71e08627af5f8961197364edbc98, < e8f9979286f70dfbfe0552e2a63000950841bea6	Fixed in e8f9979286f70dfbfe0552e2a63000950841bea6
LinuxLinux	Affected ≥ a2f79227138c71e08627af5f8961197364edbc98, < d4fd251e3311727c32af89344d3332f788c153a2	Fixed in d4fd251e3311727c32af89344d3332f788c153a2
LinuxLinux	Affected ≥ a2f79227138c71e08627af5f8961197364edbc98, < 1301a1292c6742b4c96a18715d49f89c3caca0d7	Fixed in 1301a1292c6742b4c96a18715d49f89c3caca0d7
LinuxLinux	Affected ≥ a2f79227138c71e08627af5f8961197364edbc98, < 30d7fea767e830bd81ac2f73d2e33c877cb2e679	Fixed in 30d7fea767e830bd81ac2f73d2e33c877cb2e679
LinuxLinux	Affected ≥ a2f79227138c71e08627af5f8961197364edbc98, < 8a60ade2277e1f0e0d0578d565354e52292fa46d	Fixed in 8a60ade2277e1f0e0d0578d565354e52292fa46d

AI-suggested

A fix is available and has been applied in multiple Linux kernel commits. Systems should be updated to a kernel version containing these fixes. The patch bounds the classify traversal with a drift budget to prevent infinite loops. No additional mitigation is required beyond applying the official fix.

Description

CVE-2026-98610 is a vulnerability in the Linux kernel's net/sched subsystem, specifically in the sch_hfsc classifier. It involves an unbounded classify inner-filter walk that can cause a soft lockup by endlessly looping between two interior classes when their levels drift after bind time. This results in the kernel's watchdog detecting a CPU soft lockup, potentially causing system instability or panic. The issue can be triggered by unprivileged users with CAP_NET_ADMIN via network namespace unsharing. A fix has been implemented to bound the traversal with a drift budget, dropping packets and logging warnings when the budget is exhausted.

Impact

The vulnerability causes a kernel soft lockup by indefinitely looping in the classify function while holding critical locks, which can freeze the CPU core for extended periods. This can lead to system instability, degraded performance, or kernel panic if softlockup_panic is enabled. The issue can be exploited locally by unprivileged users with CAP_NET_ADMIN privileges in a network namespace, potentially leading to denial of service on the affected system.

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 26 Oct 2026, 10:09 UTC

Technical details

References

Community reviews

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