Linux Kernel GRO Zero-Copy Skb Merge Causing UAF
CVE-2026-46323 Published on June 9, 2026
net: gro: don't merge zcopy skbs
In the Linux kernel, the following vulnerability has been resolved:
net: gro: don't merge zcopy skbs
skb_gro_receive() can currently copy frags between the source and GRO
skb, without checking the zerocopy status, and in particular the
SKBFL_MANAGED_FRAG_REFS flag.
When SKBFL_MANAGED_FRAG_REFS is set, the skb doesn't hold a reference
on the pages in shinfo->frags. Appending those frags to another skb's
frags without fixing up the page refcount can lead to UAF.
When either the last skb in the GRO chain (the one we would append
frags to) or the source skb is zerocopy, don't merge the skbs.
Vulnerability Analysis
CVE-2026-46323 can be exploited with local system access, and requires small amount of user privileges. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to be very high.
Weakness Types
Write-what-where Condition
Any condition where the attacker has the ability to write an arbitrary value to an arbitrary location, often as the result of a buffer overflow.
What is a Dangling pointer Vulnerability?
Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code.
CVE-2026-46323 has been classified to as a Dangling pointer vulnerability or weakness.
Products Associated with CVE-2026-46323
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