CVE-2026-18171: Docker Sandboxes read-only runtime mount writable through its shared-export alias

Severity: medium (CVSS 5.7 v4.0)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.1% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-08-12 · updated 2026-10-23
Weakness: CWE-863

Description

Docker Sandboxes (sbx) applies the read-only intent of a runtime host mount to the in-guest container bind only: the underlying virtio-fs host-edge grant is added to the sandbox's policy-share allowlist with no access mode. The directory stays writable at its shared-export path, so unprivileged code inside the sandbox can derive that path and write to a host directory the operator attached read-only.

Affected products

Docker Sandboxes: from 0.35.0 through 0.38.0

References

https://docs.docker.com/ai/sandboxes/
https://docs.docker.com/ai/sandboxes/architecture/

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