CVE-2026-53221

mediumCVSS 5.5covered by 8 sourcesfirst seen 2026-06-09

It was discovered that some AMD Zen 2 processors did not properly isolate shared resources in the operation cache. A local attacker could possibly use this issue to corrupt instructions executed at a higher privilege level, resulting in privilege escalation. (CVE-2025-54518) Several security issues were discovered in the Linux kernel. An attacker could possibly use these to compromise the system. This update corrects flaws in the following subsystems: - x86 platform drivers; - Cryptographic API; - PSP security protocol; - ARM32 architecture; - ARM64 architecture; - MIPS architecture; - PowerPC architecture; - RISC-V architecture; - S390 architecture; - User-Mode Linux (UML); - x86 architecture; - Block layer subsystem; - Intel NPU Driver; - Compute Acceleration Framework; - ACPI drivers; - Auxiliary display drivers; - Drivers core; - DRBD Distributed Replicated Block Device drivers; - Rados block device (RBD) driver; - Ublk userspace block driver; - Compressed RAM block device driver; - Bluetooth drivers; - Bus devices; - Character device driver; - Clock framework and drivers; - CPU frequency scaling framework; - Hardware crypto device drivers; - Buffer Sharing and Synchronization framework; - DPLL subsystem; - EDAC drivers; - Arm Firmware Framework for ARMv8-A(FFA); - EFI core; - FWCTL subsystem; - GPIO subsystem; - GPU drivers; - HID subsystem; - Hardware monitoring drivers; - I2C subsystem; - I3C subsystem; - IIO ADC drivers; - IIO subsystem; - InfiniBand drivers; - Input Device core drivers; - Input Device (Mouse) drivers; - IOMMU subsystem; - Mailbox framework; - Multiple devices driver; - Media drivers; - NVIDIA Tegra memory controller driver; - MTD block device drivers; - Network drivers; - Ethernet bonding driver; - Mellanox network drivers; - Microsoft Azure Network Adapter (MANA) driver; - STMicroelectronics network drivers; - Texas Instruments network drivers; - MediaTek network drivers; - NVME drivers; - Parport drivers; - PCI subsystem; - PHY drivers; -

CSIRTS triage

What: The vulnerability involves incorrect tunnel matching in the vti6_tnl_lookup function.
Who is affected: Deployments using the affected ip6_vti functionality.
Urgency: Remediation is medium due to the severity rating of 5.5.
Action: Apply the patch for CVE-2026-53221.

AI-assisted analysis generated from the source advisory — verify against the original.

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Exploitation outlook

Low exploitation risk0.51% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 42% of all EPSS-scored CVEs.

Advisory coverage (8)

unknownUSN-8664-1: Linux kernel (NVIDIA BaseOS) vulnerabilitiesubuntu · 2026-08-20
unknownUSN-8663-1: Linux kernel (NVIDIA) vulnerabilitiesubuntu · 2026-08-20
unknownUSN-8660-1: Linux kernel vulnerabilitiesubuntu · 2026-08-20
unknownUSN-8629-3: Linux kernel (HWE) vulnerabilitiesubuntu · 2026-08-18
unknownUSN-8629-2: Linux kernel (AWS) vulnerabilitiesubuntu · 2026-08-17
unknownUSN-8637-1: Linux kernel (OEM) vulnerabilitiesubuntu · 2026-08-13
unknownUSN-8629-1: Linux kernel vulnerabilitiesubuntu · 2026-08-12
mediumCVE-2026-53221: ip6_vti: fix incorrect tunnel matching in vti6_tnl_lookup()msrc · 2026-06-09

External references

NVD record for CVE-2026-53221

CVE.org record

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