CVE-2026-93318 Cache poisoning via unvalidated image layer DiffIDs
Attackers can poison BuildKit cache with malicious layers, leading to arbitrary code execution and secret theft during subsequent builds.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2026-93318?
CVE-2026-93318 is a high-severity vulnerability in moby BuildKit, published on 5 Oct 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official description
A malicious image can advertise DiffIDs from another image while containing different layer contents. In affected versions, BuildKit could use the advertised DiffIDs to derive cache and snapshot identity without validating that they matched the actual layer contents.
If a BuildKit daemon with shared or persistent cache first processes such a malicious image, a later build using the victim image may mount the attacker-controlled layer contents as the base image. This can allow code from the malicious image to run in the victim build, for example by replacing a commonly executed path such as /bin/sh. The attacker-controlled code may read build secrets mounted into the build, access other build resources, alter output artifacts, or hang the build.
The issue affects both regular snapshotters and lazy-pulling snapshotters such as stargz.
Weakness: CWE-354
Which versions are affected by CVE-2026-93318?
How do I fix CVE-2026-93318?
No fix has been published for CVE-2026-93318 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-93318 being exploited?
There is no known exploitation of CVE-2026-93318 in the wild and no public exploit code.
Sources
Also known as AZL-106818, GHSA-f2v9-hprr-32q3, UBUNTU-CVE-2026-93318.