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Linux Kernel: CVE-2026-53266 (Out-of-Bounds Write) Outage

  1. Investigating(current)
  2. Trending(upcoming)
  3. Workaround available(upcoming)
  4. Resolved(upcoming)

Executive summary

A critical security vulnerability in the Linux kernel has been identified, leading to an outage. No specific version or configuration is affected; all systems running the vulnerable kernel are at risk.

No verified workaround yet

None of the linked reports describe a mitigation. Follow this incident to hear when one appears.

Official fix
Technical root cause

Under active investigation. No report has identified a root cause yet.

Evidence

3 reports · 3 CVEShow
  1. [1]
    CVE First report
    Linux Kernel: CVE-2026-53266 (Out-of-Bounds Write)(opens security advisory in a new tab)

    Required action: Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching…

    by CISA KEV 0upvotes 0comments

  2. [2]
    CVE
    Linux Kernel: CVE-2025-39964 (Race Condition)(opens security advisory in a new tab)

    Required action: Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching…

    by CISA KEV 0upvotes 0comments97% match

  3. [3]
    CVE
    Linux Kernel: CVE-2025-39682 (Improper Check for Unusual or Exceptional Conditions)(opens security advisory in a new tab)

    Required action: Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching…

    by CISA KEV 0upvotes 0comments98% match

Timeline

  1. First report on security advisory

    Linux Kernel: CVE-2026-53266 (Out-of-Bounds Write)

    Source