CVE-2026-33748 BuildKit Git URL subdir component can cause access to restricted files
Attackers can access restricted files outside the Git repository root via malicious Git URL subdir components in BuildKit builds.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-33748?
CVE-2026-33748 is a high-severity path traversal vulnerability in moby buildkit, published on 27 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
BuildKit is a toolkit for converting source code to build artifacts in an efficient, expressive and repeatable manner. Prior to version 0.28.1, insufficient validation of Git URL fragment subdir components may allow access to files outside the checked-out Git repository root. Possible access is limited to files on the same mounted filesystem. The issue has been fixed in version v0.28.1 The issue affects only builds that use Git URLs with a subpath component. As a workaround, avoid building Dockerfiles from untrusted sources or using the subdir component from an untrusted Git repository where the subdir component could point to a symlink.
Which versions are affected by CVE-2026-33748?
3 open source packages ship an affected version, including github.com/moby/buildkit. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
github.com/moby/buildkit Go | All versions | 0.28.1 |
github.com/moby/buildkit Go | All versions | 0.28.1 |
github.com/moby/buildkit Go | All versions | 0.28.1 |
Products include Mobyproject Buildkit.
How do I fix CVE-2026-33748?
Upgrade github.com/moby/buildkit to 0.28.1 or later.
Upgrade, and resolve every user-supplied path against an allowed base folder before opening it. More about Path traversal.
Is CVE-2026-33748 being exploited?
There is no known exploitation of CVE-2026-33748 in the wild and no public exploit code.
Other vulnerabilities in moby buildkit
- CVE-2024-23652 BuildKit possible host system access from mount stub cleaner
- CVE-2024-23653 BuildKit interactive containers API does not validate entitlements check
- CVE-2024-23651 BuildKit possible race condition with accessing subpaths from cache mounts
- CVE-2026-33747 BuildKit vulnerable to malicious frontend causing file escape outside of storage root
- CVE-2026-15789 Malicious client can bypass destination directory validation on local sources upload
Sources
Also known as BELL-CVE-2026-33748, CLEANSTART-2026-BN78541, CLEANSTART-2026-CI85082, CLEANSTART-2026-HI94719, CLEANSTART-2026-ZT40995, DEBIAN-CVE-2026-33748 and 29 more.