Bug 2486987 (CVE-2026-46322)

Summary: CVE-2026-46322 kernel: tun: free page on build_skb failure in tun_xdp_one()
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
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Priority: medium    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
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Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's `tun` driver. This vulnerability occurs when the `build_skb()` function fails within `tun_xdp_one()`, leading to a failure to free an allocated memory page. Each such failure results in a memory leak, where a 'page-frag chunk' is not released. Over time, repeated exploitation of this flaw could lead to memory exhaustion, resulting in a Denial of Service (DoS) for the system.
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Description OSIDB Bzimport 2026-06-09 13:01:45 UTC 
In the Linux kernel, the following vulnerability has been resolved:

tun: free page on build_skb failure in tun_xdp_one()

When build_skb() fails in tun_xdp_one(), the function sets ret to
-ENOMEM and jumps to the out label, which returns without freeing the
page that vhost_net_build_xdp() allocated for the frame. As with the
short-frame rejection path, tun_sendmsg() discards the per-buffer error
and still returns total_len, so vhost_tx_batch() takes the success path
and never frees the page. Each build_skb() failure in a batch leaks one
page-frag chunk.

Free the page before taking the error path, matching the put_page() the
other error exits of tun_xdp_one() already perform.
Comment 1 Keith Grant 2026-06-09 16:50:08 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026060925-CVE-2026-46322-15c5@gregkh/T