---
id: CVE-2026-46695
aliases:
  - RUSTSEC-2026-0147
  - GHSA-g6ww-w5j2-r7x3
  - GO-2026-5392
  - PYSEC-2026-299
title: Read-only volume remount bypass via guest CAP_SYS_ADMIN
summary: Read-only volume remount bypass via guest CAP_SYS_ADMIN
severity: critical
cvss: 10
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H'
vendor: boxlite
product: boxlite
ecosystem: rust
affected:
  - 'boxlite >= 0.0.0-0, < 0.9.0'
patched:
  - boxlite 0.9.0
published: '2026-05-16'
updated: '2026-10-12'
sourceUpdated: '2026-10-12T18:00:13.061473890Z'
source: OSV
sourceUrl: 'https://osv.dev/vulnerability/RUSTSEC-2026-0147'
references:
  - url: 'https://crates.io/crates/boxlite'
  - url: 'https://rustsec.org/advisories/RUSTSEC-2026-0147.html'
  - url: 'https://github.com/boxlite-ai/boxlite/pull/454'
  - url: 'https://github.com/boxlite-ai/boxlite/pull/454'
  - url: >-
      https://github.com/boxlite-ai/boxlite/security/advisories/GHSA-g6ww-w5j2-r7x3
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-46695'
  - url: 'https://github.com/boxlite-ai/boxlite'
  - url: 'https://github.com/boxlite-ai/boxlite/releases/tag/v0.9.0'
tags:
  - osv
  - rust
  - pip
epss: 0.00289
epssPercentile: 0.21327
ingestedAt: '2026-09-12T03:13:01.694Z'
---

## Overview

Affected versions of `boxlite` mount host directories shared via virtiofs
as guest-side read-only by setting `MS_RDONLY` from the guest. Because the
default guest capability set included `CAP_SYS_ADMIN`, untrusted code
running inside a sandbox could execute `mount -o remount,rw <path>` to
re-flag the share as read-write and then write through to the host
filesystem — fully escaping the read-only contract `boxlite` advertised
to callers.

The fix in v0.9.0 enforces read-only at the hypervisor level via
`krun_add_virtiofs3` (so the guest's `MS_RDONLY` is no longer the
authoritative gate) and drops `CAP_SYS_ADMIN` from the default guest
capability set (matching Docker's defaults).

This is a sandbox-escape bug: `boxlite` is a sandboxing runtime, so the
read-only invariant is part of its security contract. CVSS rated 10.0 by
the upstream advisory.

## Affected packages

- `boxlite >= 0.0.0-0, < 0.9.0`

## Remediation

Upgrade to a patched release:

- `boxlite 0.9.0`