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CVE-2026-45909 Linux CVE debrief

A vulnerability in the Linux kernel's Mediatek clock driver has been resolved. The issue stemmed from incorrect use of the `__initconst` annotation on `mtk_gate` structures. Following a refactoring in commit 8ceff24a754a, these structures are accessed at runtime, not just during initialization. The `__initconst` annotation causes the kernel to discard this data after boot, leading to use-after-free or invalid memory access when the clock gates are accessed later. The fix removes the `__initconst` annotations to ensure the structures remain available throughout system operation.

Vendor
Linux
Product
Unknown
CVSS
Unknown
CISA KEV
Not listed in stored evidence
Original CVE published
2026-05-27
Original CVE updated
2026-05-27
Advisory published
2026-05-27
Advisory updated
2026-05-27

Who should care

Organizations running Linux on Mediatek SoCs (common in mobile devices, IoT, and embedded systems) should prioritize this patch to prevent system instability. Kernel maintainers and distributors should backport the fix to affected stable branches.

Technical summary

The Mediatek clock gate driver in the Linux kernel incorrectly retained `__initconst` annotations on `mtk_gate` structures after a refactoring (commit 8ceff24a754a) changed their usage from initialization-only to runtime. The `__initconst` section attribute instructs the kernel to discard the data after boot, causing subsequent runtime accesses to read freed/invalid memory. This can result in undefined behavior, system crashes, or potential security implications on Mediatek-based systems. The fix removes the `__initconst` annotations to ensure the structures persist for the lifetime of the kernel.

Defensive priority

medium

Recommended defensive actions

  • Apply the relevant stable kernel patch for your kernel version: 5.15.y, 6.1.y, or 6.6.y branches
  • Rebuild and deploy updated kernel with patched Mediatek clock driver
  • Verify `__initconst` is removed from `mtk_gate` definitions in `drivers/clk/mediatek/`
  • For systems using Mediatek SoCs, prioritize patching to prevent potential system instability or crashes from invalid memory access to clock gate structures

Evidence notes

The CVE description explicitly states the vulnerability is resolved and identifies the root cause: `__initconst` annotations on `mtk_gate` structs that are now used at runtime following commit 8ceff24a754a. Three stable kernel patches are referenced.

Official resources

The vulnerability was disclosed via the Linux kernel stable tree with patches published on 2026-05-27. The issue was introduced when the Mediatek clock gate driver was refactored to use `mtk_gate` structs at runtime, but the `__initconst`修饰