---
id: "CVE-2026-99057"
kind: "vulnerability"
aliases: ["CVE-2026-99057"]
title: "Linux kernel: Xen netfront leaks socket buffers when packet chains overflow"
severity: "unknown"
cvss: null
epss: 0.00209
exploited: false
status: "open"
category: "infrastructure"
products: []
ecosystems: []
tags: ["infrastructure", "linux-kernel", "xen", "xen-guests"]
not_affected_if: ["kvm-or-bare-metal", "non-xen-hosts"]
published_at: "2026-10-23T13:17:29+00:00"
first_seen_at: "2026-10-23T21:57:33+00:00"
updated_at: "2026-10-25T12:38:50+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-99057", "first_seen_at": "2026-10-23T21:57:33+00:00"}, {"source": "epss", "url": "https://api.first.org/data/v1/epss?cve=CVE-2026-99057", "first_seen_at": "2026-10-25T12:38:50+00:00"}]
---

# Linux kernel: Xen netfront leaks socket buffers when packet chains overflow

In the Linux kernel's Xen network frontend (netfront), a receive path that fails to fit a response chain into an skb leaks that skb and its attached pages. The backend controls how many slots it sends, so each overflowing chain leaks memory.

_Summary, check and fix written by a model from the sources; labelled as such._

## Timeline

- 2026-10-23T21:57:33+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-99057
- 2026-10-25T12:38:50+00:00 epss https://api.first.org/data/v1/epss?cve=CVE-2026-99057

## From the sources

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.

---

_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_