CVE-2026-99057: xen/netfront: don't leak the skb when xennet_fill_frags() fails

Severity: unknown
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-10-23 · updated 2026-10-30

Description

In the Linux kernel, the following vulnerability has been resolved: xen/netfront: don't leak the skb when xennet_fill_frags() fails When a response chain has more slots than fit in the skb's frags, xennet_fill_frags() returns an error and xennet_poll() jumps to its error path. That path moves what's left on tmpq to errq to be freed, but the skb being filled was already dequeued from tmpq, so it's never freed. Each chain that overflows leaks the skb and the pages attached to it as frags, and the backend decides how many slots it sends. Put the skb back on tmpq before taking the error path, like the xennet_set_skb_gso() failure just above it does.

Affected products

Linux: from 4.4.159 before 4.5; from 4.9.130 before 4.10; from 4.14.73 before 4.15; from 4.18.11 before 4.19 — fixed in 4.5, 4.10, 4.15, 4.19

How to fix

Upgrade to a fixed version: Linux 4.5, 4.10, 4.15, 4.19. Check the vendor advisory for mitigations.

References

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