Linux Kernel: security vulnerability (CVE-2026-99104)

What is affected, what to do

In the Linux kernel, the following vulnerability has been resolved: sched_ext: Fix the bypass dispatch claim for schedulers bypassed by an ancestor scx_bypass() claims bypass dispatch when the scheduler's depth goes from zero to one and releases it when the depth returns to zero, but propagates only the depth to the descendants, not the claim. A descendant that starts bypassing with its ancestor never claims, and one whose own bypass ends under the ancestor's keeps its claim, as its depth does not return to zero.

Update Linux Kernel to version 7.2.13, Linux Kernel to version 7.3.

Affected

• Linux Kernel lt 7.1..7.2.13

Fixed in

• Linux Kernel 7.2.13
• Linux Kernel 7.3

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Metrics

Detection rules

No NEOSEC detection rule is available for this vulnerability yet.

Classification under NIS2 and CRA

Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.

NIS2

NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management.

Read in glossary

Handle the vulnerability in regular vulnerability handling under Art. 21(2)(e) NIS2.

CRA

The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates.

Read in glossary

From 11.12.2027, Annex I Part II CRA requires manufacturers of affected products with digital elements to handle vulnerabilities without delay and provide security updates.

ISO/IEC 27001

ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security.

Read in glossary

Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.

Description

In the Linux kernel, the following vulnerability has been resolved: sched_ext: Fix the bypass dispatch claim for schedulers bypassed by an ancestor scx_bypass() claims bypass dispatch when the scheduler's depth goes from zero to one and releases it when the depth returns to zero, but propagates only the depth to the descendants, not the claim. A descendant that starts bypassing with its ancestor never claims, and one whose own bypass ends under the ancestor's keeps its claim, as its depth does not return to zero. A sub-scheduler enable whose bypass ends under a PM suspend thus leaks its claim: the parent keeps hosting bypass dispatch and the sub-scheduler's next bypass trips the WARN_ON_ONCE() on the claim. A sub-scheduler disable that starts under a PM suspend has no claim, so once the resume lifts the root's bypass its tasks sit on the parent's bypass DSQs with nobody consuming them. Claim for every descendant whose depth goes from zero to one in the propagation and release every scheduler in the subtree whose depth returned to zero once the tasks have moved out of the bypass DSQs. A parent that is bypassing itself when a descendant claims consumes only its own bypass DSQs, empty until it leaves bypass and becomes the host.

Source: BSI CSAF, BSI WID Portal, cvelistv5, NVD (NIST)

Vendors and products

• Linux Linux

References & sources

• git.kernel.orgstable/c/5bdeca322a6f8d10acaf67cccab1f69747ee7be3
• git.kernel.orgstable/c/f0f18075e45d47bef7ff2eb9512ee4f0c7e5f9c7

Changes to this CVE

Who changed this CVE and when: NVD (analysis, affected products, CVSS), the CVE publisher (CNA) and additional providers such as CISA (ADP).

1. 28.10.2026ReceivedLinux

   Description added or changed

   New references:

   • https://git.kernel.org/stable/c/5bdeca322a6f8d10acaf67cccab1f69747ee7be3
   • https://git.kernel.org/stable/c/f0f18075e45d47bef7ff2eb9512ee4f0c7e5f9c7
   Show 4 original changes

   Individual changes of this event as published by NVD

   Type	Action	Before	After
   Description	added	—	In the Linux kernel, the following vulnerability has been resolved: sched_ext: Fix the bypass dispatch claim for schedulers bypassed by an ancestor scx_bypass() claims bypass dispatch when the scheduler's depth goes from zero to one and releases it when the depth returns to zero, but propagates only the depth to the descendants, not the claim. A descendant that starts bypassing with its ancestor never claims, and one whose own bypass ends under the ancestor's keeps its claim, as its depth does not return to zero. A sub-scheduler enable whose bypass ends under a PM suspend thus leaks its claim: the parent keeps hosting bypass dispatch and the sub-scheduler's next bypass trips the WARN_ON_ONCE() on the claim. A sub-scheduler disable that starts under a PM suspend has no claim, so once the resume lifts the root's bypass its tasks sit on the parent's bypass DSQs with nobody consuming them. Claim for every descendant whose depth goes from zero to one in the propagation and release every scheduler in the subtree whose depth returned to zero once the tasks have moved out of the bypass DSQs. A parent that is bypassing itself when a descendant claims consumes only its own bypass DSQs, empty until it leaves bypass and becomes the host.
   Affected versions (publisher)	added	—	New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/99xxx/CVE-2026-99104.json">CVE-2026-99104</a>
   Reference	added	—	https://git.kernel.org/stable/c/5bdeca322a6f8d10acaf67cccab1f69747ee7be3
   Reference	added	—	https://git.kernel.org/stable/c/f0f18075e45d47bef7ff2eb9512ee4f0c7e5f9c7

   Source identifier: 416baaa9-dc9f-4396-8d5f-8c081fb06d67