CVE-2026-64336 Linux CVE debrief

Who should care

Linux kernel maintainers, users, and administrators should assess their exposure and apply patches to prevent potential information leaks. The vulnerability affects Linux kernel versions and could lead to potential information leaks if not patched. Users and administrators should verify the affected versions and apply patches to prevent potential information leaks.

Why it matters

CVE-2026-64336 is a medium-severity vulnerability in the Linux kernel that can lead to an information leak. Linux kernel maintainers and users should assess exposure and apply patches to prevent potential information leaks.

• Potential information leak due to incorrect return value
• Need to verify and apply patches to affected Linux kernel versions

Technical summary

The Linux kernel vulnerability (CVE-2026-64336) is caused by the keyspan_pda driver's write() callback not returning the correct number of characters accepted or a negative errno. This can lead to an information leak. The vulnerability affects Linux kernel versions and could lead to potential information leaks if not patched. Users and administrators should assess their exposure and apply patches to prevent potential information leaks. The vulnerability has been resolved with several patches available. The write() callback is supposed to return the number of characters accepted or a negative errno.

Defensive priority

Medium priority for Linux kernel maintainers and users

Recommended defensive actions

• Apply patches provided by Linux kernel maintainers
• Review and update Linux kernel versions to ensure vulnerability is patched
• Verify the integrity of the Linux kernel versions
• Check for any exposed systems and assign an owner for follow-up
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Track exceptions, retest remediated assets, and close the item only after evidence is documented
• Confirm whether affected product deployments exist in managed environments

Evidence notes

The CVE record and NVD entry provide details on the vulnerability, including its description and affected versions. The vulnerability has been resolved with several patches available. Linux kernel maintainers and users should verify the affected versions and apply patches to prevent potential information leaks. The write() callback is supposed to return the number of characters accepted or a negative errno. Since the addition of write fifo support the keyspan_pda implementation will however return the number characters submitted to 0

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.