CVE-2026-53363
A critical flaw in the Linux kernel’s IPsec fragment handling can allow attackers to compromise confidentiality, integrity, and availability. The bug occurs when shared fragment markers are not preserved during fragment consumption, potentially enabling in‑place encryption to be misapplied. The issue has been fixed in the kernel; upgrading resolves it.
An official fix is available, so this entry is kept for 30 days and then removed automatically.
Who is affected
Linux kernel (all versions before the patch) – any system running an affected kernel, especially those using IPsec with fragment handling.
Real-world impact
An attacker could exploit the flaw to read, modify, or disrupt network traffic protected by IPsec, potentially gaining full control over the affected system.
Why this severity
The CVSS score of 9.8 reflects that the vulnerability is exploitable over the network with no authentication or user interaction, and it can compromise confidentiality, integrity, and availability of all data passing through the kernel.
What to do about it
- 01Update the Linux kernel to a version that includes the fix for CVE-2026-53363.
- 02Reboot or reload the kernel to apply the update.
NVD-referenced vendor advisory
Timeline
- Jul 10, 2026 · 25d agoPublishedDisclosed and added to the National Vulnerability Database.
- Jul 19, 2026 · 16d agoOfficial fix availableA vendor patch or mitigation now exists — see the remediation steps above.
- Jul 22, 2026 · 12d agoAdvisory updatedThe NVD record was last revised.