CVE-2026-98942 Linux CVE debrief

Who should care

Linux kernel maintainers, users, and administrators should assess exposure and prioritize verification of affected versions. Affected operator, platform, vulnerability-management, and security-team impact should be evaluated to ensure proper mitigation and remediation.

Why it matters

A vulnerability in the Linux kernel's sched_ext component has been addressed, potentially allowing racing programs to read unfilled or uninitialized memory in cid tables. Linux kernel maintainers and users should assess exposure and prioritize verification of affected versions.

• Read unfilled or uninitialized memory in cid tables
• Potential data exposure or corruption
• Verification of affected versions required
• Patching or updating Linux kernel versions may be necessary

Technical summary

The Linux kernel's sched_ext component had a vulnerability where cid tables were visible to cid kfuncs while being modified. This could allow racing programs to read unfilled entries, including uninitialized memory. The fix builds cid tables privately and publishes them with RCU, ensuring that a non-NULL global is now always a fully built table which stays valid for the reader's RCU read section, and lookups stay two loads. Kfuncs treat NULL as no-mapping, also after the scheduler exits instead of reporting the stale last mapping.

Defensive priority

Linux kernel maintainers and users should assess exposure and prioritize verification of affected versions.

Recommended defensive actions

• Review Linux kernel versions for exposure
• Verify affected versions using official sources
• Apply patches or updates as recommended by Linux kernel maintainers
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented

Evidence notes

The CVE Program record and NVD vulnerability detail provide official information on the vulnerability. Supplemental sources include kernel.org references. Linux kernel maintainers and users should verify affected versions and assess exposure. The cid tables were visible to cid kfuncs while being modified, potentially allowing racing TRACING or SYSCALL programs to read unfilled entries, including uninitialized memory. The fix ties the tables' lifetimes to the root sched, building a fresh set privately and publishing per-table __rcu

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.