# 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.

- **Severity:** High 7.5 (`CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:H/VI:H/VA:L/SC:N/SI:N/SA:N`)
- **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 available:** No
- **Published:** 5 Oct 2026
- **Updated:** 5 Oct 2026
- **Also known as:** AZL-106818, GHSA-f2v9-hprr-32q3, UBUNTU-CVE-2026-93318

## 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 (Improper Validation of Integrity Check Value)

## 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.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-93318 and fix it if it is affected.

What it is: 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.
Exploitation: There is no known exploitation of CVE-2026-93318 in the wild and no public exploit code.

Affected product: moby BuildKit. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-93318/ (Markdown: https://insights.sbomify.com/CVE-2026-93318/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-93318
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-93318
- OSV: https://osv.dev/vulnerability/CVE-2026-93318

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-93318/
Summaries are generated and may contain mistakes; the official description above is the record.