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CVE-2026-99279

CVE-2026-99279

What's the vulnerability?

In the Linux kernel, the following vulnerability has been resolved: ksmbd: reclaim ended sessions on logoff and expiration LOGOFF and previous-session replacement leave sessions Expired with a zero credential expiry. Ended sessions can retain their memory and connection slots when no further setup arrives on the owning connection. Unpublish a logged-off session while the request reference keeps its response signing and encryption keys alive. Remove its procfs entry before dropping the table reference so a reader cannot remove its own entry on the last put. Clear proc_entry after removal to avoid removing it twice. Reclaim ended sessions from the global table in the existing expiration worker before it acquires conn_list_lock. Only select Expired sessions with zero credential expiry and no references beyond the table reference. Keep sessions whose Kerberos credentials expired available for reauthentication. Unlink the session from its setup connection and all channel connections, so SMB2 sessions and sessions with only secondary SMB3 channels are covered. The session already holds connection references, and sessions_table_lock prevents concurrent channel removal. Queue sessions on a separate disposal list, leaving their hash nodes unhashed, and remove procfs entries and drop table references outside the locks. Keep the pending setup check before allocating a new session so abandoned InProgress sessions can release their slots even at the connection limit. Retain the timeout and reference checks and dispose of those sessions outside the locks. Leave ended Expired sessions to the expiration worker.

R4IM analyst take

Business impact & how R4IM helps

This advisory is on our active-exploitation watchlist. Attackers are using it for initial access, privilege escalation or lateral movement in real-world intrusions. R4IM's offensive security and SOC teams already have detections, exploit replicas and remediation playbooks for this issue.

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Prove it with a pentest

Our pentesters chain this CVE into realistic attack paths so you see business impact, not just a scan finding.

Web app security testing

If the affected product is internet-facing, our AppSec team will harden it against this and related OWASP-class issues.

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Continuous monitoring with custom detections for this CVE deployed across your endpoints, identity and cloud.

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Recommended remediation

  1. Inventory all assets running the affected vendor and product, including shadow IT and third-party hosted instances.
  2. Apply the vendor patch or mitigation referenced in the advisories below. Where no patch exists, isolate the asset or restrict network exposure.
  3. Hunt for indicators of prior compromise — exploitation of this class of bug often predates public disclosure.
  4. Deploy detections for the exploit primitives (network signature, EDR rule, WAF rule) and re-test after remediation.

Need help executing these steps? Our team typically completes validation and remediation within a single patch cycle. Request remediation support →

Vendor & research references