CVE-2026-98935 Linux CVE debrief

Who should care

Defenders responsible for Linux kernel deployments, particularly those using the rtc: dev module, should assess exposure and prioritize patch application. This includes operators, platform administrators, vulnerability management teams, and security teams who need to review and apply patches to prevent potential information leaks. Inventory and assessment of Linux kernel deployments are necessary to determine the level of exposure and to plan for patching.

Why it matters

The Linux kernel vulnerability in the rtc: dev module may lead to information leaks. Defenders should verify and apply patches, inventory and assess exposure, and monitor updates.

• Potential information leak via uninitialized kernel stack data
• Verification of Linux kernel versions and patch application required
• Inventory and assessment of Linux kernel deployments necessary

Technical summary

The struct rtc_wkalrm in the Linux kernel has padding holes after the 'pending' member. When returned to userspace via the RTC_WKALRM_RD ioctl, uninitialized kernel stack data residing in these holes may be leaked. Zero-initializing the struct at declaration eliminates this information leak risk. The vulnerability affects Linux kernel deployments using the rtc: dev module, and defenders should prioritize verifying and applying patches for affected systems. The CVE record and source item provide details on the vulnerability, including its description and affected versions.

Defensive priority

Defenders should prioritize verifying and applying patches for Linux kernel versions affected by this vulnerability, particularly for systems using the rtc: dev module.

Recommended defensive actions

• Verify Linux kernel versions and apply patches for affected systems using the rtc: dev module
• Inventory and assess exposure of Linux kernel deployments
• Monitor Linux kernel updates and verify patch application
• 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
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

The CVE record and source item provide details on the vulnerability, including its description and affected versions. However, the corpus does not establish specific exploitation or impact, requiring verification from official sources.

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.