Read-only volume remount bypass via guest CAP_SYS_ADMIN

{
  "id": "755f9032bef3cd70bff9c1e950da65442fb84097b777a6a9a7f618ba08aa6ad1",
  "url": "https://osv.dev/vulnerability/RUSTSEC-2026-0147",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Read-only volume remount bypass via guest CAP_SYS_ADMIN",
    "summary": "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 ` 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.",
    "evidence": "osv:RUSTSEC-2026-0147",
    "products": [
      {
        "name": {
          "value": "boxlite",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "0.9.0",
            "evidence": "/affected/0/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "critical",
    "structured": {
      "id": "RUSTSEC-2026-0147",
      "aliases": [
        "CVE-2026-46695",
        "GHSA-g6ww-w5j2-r7x3",
        "GO-2026-5392",
        "PYSEC-2026-299",
        "RUSTSEC-2026-0147"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "SEMVER",
              "events": [
                {
                  "introduced": "0.0.0-0"
                },
                {
                  "fixed": "0.9.0"
                }
              ]
            }
          ],
          "package": {
            "name": "boxlite",
            "purl": "pkg:cargo/boxlite",
            "ecosystem": "crates.io"
          },
          "database_specific": {
            "cvss": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H",
            "source": "https://github.com/rustsec/advisory-db/blob/osv/crates/RUSTSEC-2026-0147.json",
            "categories": [
              "privilege-escalation"
            ],
            "informational": null
          },
          "ecosystem_specific": {
            "affects": {
              "os": [],
              "arch": [],
              "functions": []
            },
            "affected_functions": null
          }
        }
      ],
      "modified": "2026-10-12T18:00:13.061473890Z",
      "provider": "osv",
      "references": [
        "https://crates.io/crates/boxlite",
        "https://rustsec.org/advisories/RUSTSEC-2026-0147.html",
        "https://github.com/boxlite-ai/boxlite/pull/454"
      ],
      "provider_metadata": {
        "license": "CC0-1.0"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-46695",
        "evidence": "/aliases"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 306439,
  "published_at": "2026-05-16T12:00:00+00:00"
}