CVE-2026-53247: net: ethernet: mtk_eth_soc: Fix use-after-free in metadata dst teardown

Severity: critical (CVSS 9.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.7% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-06-25 · updated 2026-07-07
Weakness: CWE-416

Description

In the Linux kernel, the following vulnerability has been resolved: net: ethernet: mtk_eth_soc: Fix use-after-free in metadata dst teardown mtk_free_dev() calls metadata_dst_free() which frees the metadata_dst with kfree() immediately, bypassing the RCU grace period. In the RX path, skb_dst_set_noref() sets a non-refcounted pointer from the skb to the metadata_dst. This function requires RCU read-side protection and the dst must remain valid until all RCU readers complete. Since metadata_dst_free() calls kfree() directly, a use-after-free can occur if any skb still holds a noref pointer to the dst when the driver tears it down. Replace metadata_dst_free() with dst_release() which properly goes through the refcount path: when the refcount drops to zero, it schedules the actual free via call_rcu_hurry(), ensuring all RCU readers have completed before the memory is freed.

Affected products

Linux kernel: from 6.2 before 6.6.143; from 6.7 before 6.12.94; from 6.13 before 6.18.36; from 6.19 before 7.0.13; 7.1-rc1, 7.1-rc2, 7.1-rc3, 7.1-rc4, 7.1-rc5, 7.1-rc6 — fixed in 6.12.94, 6.18.36, 6.6.143, 7.0.13

How to fix

Upgrade to a fixed version: Linux kernel 6.12.94, 6.18.36, 6.6.143, 7.0.13. Check the vendor advisory for mitigations.

References

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