CVE-2026-121520

In BuildKit versions v0.26.0 through v0.34.1, a specific build definition that resolves metadata for the same Git source reference twice can cause the BuildKit daemon to panic and crash, interrupting builds handled by that daemon.

A malicious frontend can submit an LLB definition that causes buildkitd to panic and terminate, interrupting all builds running on that daemon.

When proxy networking with CA injection is enabled, a build can modify its CA bundle before cleanup. This may cause cleanup to block, operate outside the build rootfs, or fail without failing the build.

Improper Validation of Specified Quantity in Input vulnerability in VillaTheme BuildKit – Product Builder for WooCommerce – Custom PC Builder woo-product-builder allows Input Data Manipulation.This issue affects BuildKit – Product Builder for WooCommerce – Custom PC Builder: from n/a through 1.0.28.

The Dockerfile frontend loaded Dockerfile and .dockerignore files into memory without a size limit. A build context with an oversized file could cause buildkitd to allocate memory proportional to the file size, potentially exhausting memory and terminating the daemon, interrupting other builds.

A malicious frontend can submit an LLB definition that causes buildkitd to panic and terminate, interrupting all builds running on that daemon.

BuildKit may be tricked into performing file actions with special file inodes where regular files are expected. Special files may block operations or, on rootful workers, allow unintended host device access.

A malicious external BuildKit frontend can send requests using the internal API that can create conditions for a data race that can cause the BuildKit daemon to panic.

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.

An unauthenticated attacker controlling a registry or OCI-layout blob source could provide blob contents that did not match the claimed digest. The resulting snapshot could be cached under that digest and reused by a later victim build, compromising build-input integrity.