CVE-2026-98035 Linux CVE debrief

Who should care

Linux kernel administrators, security teams, and developers using BPF or rhtab in their environments should assess exposure and prioritize verification of affected systems. This includes reviewing Linux kernel configurations and versions, verifying BPF and rhtab usage, and applying patches or updates provided by the Linux kernel maintainers. Additionally, monitoring system logs for suspicious BPF-related activity is recommended to detect potential issues.

Why it matters

CVE-2026-98035 is a vulnerability in the Linux kernel's BPF rhtab implementation that could lead to potential issues in NMI context. Defenders should verify exposure, prioritize patching, and monitor for suspicious activity.

• Verification of BPF and rhtab usage in the environment is necessary to determine potential exposure.
• Linux kernel administrators and security teams need to assess and prioritize patching or updating affected systems.
• Monitoring system logs for suspicious BPF-related activity is recommended to detect potential issues.

Technical summary

The Linux kernel vulnerability (CVE-2026-98035) involves the bpf subsystem's rhtab implementation. The problem arises from operations in NMI context, which could lead to unsafe behavior. The fix involves using `bpf_obj_cancel_fields` to safely cancel timers, workqueues, and task work when recycling rhtab elements. This change allows for proper cleanup and prevents potential issues with referenced kptrs (kernel pointers) when the allocation is eventually destroyed. The fix was introduced to address the vulnerability and ensure the stability and security of the Linux kernel.

Defensive priority

Linux kernel administrators and security teams should assess exposure and prioritize verification of affected systems, especially those with BPF or rhtab usage.

Recommended defensive actions

• Review Linux kernel configurations and versions to determine potential exposure.
• Verify BPF and rhtab usage in the environment.
• Apply patches or updates provided by the Linux kernel maintainers.
• Monitor system logs for suspicious BPF-related activity.
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up.
• Review the supplied official advisory or CVE record to validate affected scope, severity, and vendor guidance.
• Plan vendor-supported updates or mitigations through normal change control where exposure is confirmed.

Evidence notes

The CVE record and associated source references provide details on the vulnerability and its resolution in the Linux kernel. However, specific version impact and exploitation details are not provided, requiring further verification.

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.