CVE-2026-18171 Docker Sandboxes read-only runtime mount writable through its shared-export alias
Unprivileged code in Docker Sandboxes can write to host directories intended to be read-only by exploiting a shared-export alias vulnerability.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-18171?
CVE-2026-18171 is a medium-severity missing authorization vulnerability in Docker Sandboxes, published on 12 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official 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.
Weakness: CWE-863
Which versions are affected by CVE-2026-18171?
How do I fix CVE-2026-18171?
No fix has been published for CVE-2026-18171 yet. Limit exposure of the affected software until one is available.
Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.
Is CVE-2026-18171 being exploited?
There is no known exploitation of CVE-2026-18171 in the wild and no public exploit code.
Sources
Also known as GHSA-q3q4-c92f-m955.