CVE-2026-46321

CVE-2026-46321 is a high-severity vulnerability in Linux Linux Kernel with a CVSS 3.x base score of 7.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low.

Key facts

Description

In the Linux kernel, the following vulnerability has been resolved: tun: free page on short-frame rejection in tun_xdp_one() tun_xdp_one() returns -EINVAL on a frame shorter than ETH_HLEN without freeing the page that vhost_net_build_xdp() allocated for it. tun_sendmsg() discards that -EINVAL and still returns total_len, so vhost_tx_batch() takes the success path and never frees the page; each short frame in a batch leaks one page-frag chunk. A local process that can open /dev/net/tun and /dev/vhost-net can hit this path: it attaches a tun/tap device as the vhost-net backend and feeds TX descriptors whose length minus the virtio-net header is below ETH_HLEN. Each kick leaks the page-frag chunks for that batch, and a tight submission loop exhausts host memory and triggers an OOM panic. Free the page before returning -EINVAL, matching the XDP-program error path in the same function.

Frequently asked questions

What is CVE-2026-46321?
In the Linux kernel, the following vulnerability has been resolved: tun: free page on short-frame rejection in tun_xdp_one() tun_xdp_one() returns -EINVAL on a frame shorter than ETH_HLEN without freeing the page that vhost_net_build_xdp() allocated for it. tun_sendmsg() discards that -EINVAL and still returns total_len, so vhost_tx_batch() takes the success path and never frees the page; each short frame in a batch leaks one page-frag chunk. A local process that can open /dev/net/tun and /dev/vhost-net can hit this path: it attaches a tun/tap device as the vhost-net backend and feeds TX descriptors whose length minus the virtio-net header is below ETH_HLEN. Each kick leaks the page-frag chunks for that batch, and a tight submission loop exhausts host memory and triggers an OOM panic. Free the page before returning -EINVAL, matching the XDP-program error path in the same function.
How severe is CVE-2026-46321?
CVE-2026-46321 has a CVSS 3.x base score of 7.1, rated high severity. It is exploitable over local access with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2026-46321 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (3rd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-46321?
CVE-2026-46321 primarily affects Linux Linux Kernel. In total, 6 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2026-46321?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2026-46321 have an EU (EUVD) identifier?
Yes. CVE-2026-46321 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-35411.
When was CVE-2026-46321 published?
CVE-2026-46321 was published on 2026-06-09 and last updated on 2026-07-08.

References

Affected products (6)

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