CVE-2026-53212
HighCVSS 7.8Exploitation Probability (EPSS)
Low risk3th percentile — higher than 3% of all known CVEs
Summary
A use-after-free vulnerability was found in the Linux kernel's nft_tunnel module. The nft_tunnel_obj_destroy() function calls metadata_dst_free() which directly frees the metadata_dst memory, ignoring the dst_entry refcount. Packets that hold a reference via dst_hold() in nft_tunnel_obj_eval() and are still queued (e.g., in a netem qdisc) are left with a dangling pointer, leading to use-after-free when dequeued.
Risk Assessment
This vulnerability can cause system crashes (kernel panic) or potentially arbitrary code execution in kernel context, posing a serious risk to system stability and security.
Recommendation
Immediately update the Linux kernel to a version containing the fix that replaces metadata_dst_free() with dst_release(), ensuring proper reference counting.
Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: netfilter: nft_tunnel: fix use-after-free on object destroy nft_tunnel_obj_destroy() calls metadata_dst_free() which directly kfree()s the metadata_dst, ignoring the dst_entry refcount. Packets that took a reference via dst_hold() in nft_tunnel_obj_eval() and are still queued (e.g. in a netem qdisc) are left with a dangling pointer. When these packets are eventually dequeued, dst_release() operates on freed memory. Replace metadata_dst_free() with dst_release() so the metadata_dst is freed only after all references are dropped. The dst subsystem already handles metadata_dst cleanup in dst_destroy() when DST_METADATA is set.