Executive brief
apko is a tool used to build secure container images from software packages. A security flaw was found where the tool failed to verify the integrity of individual packages during the build process, even if the main index was signed. This allows an attacker who controls a package mirror or network traffic to inject malicious software into the resulting container images, potentially compromising any systems where those images are deployed.
Technical details
A vulnerability exists in apko's package retrieval logic within the getPackageImpl() function. While the tool correctly verifies the signature of the APKINDEX.tar.gz file, it fails to compare the computed hash of downloaded .apk files against the checksums defined in that signed index. An attacker capable of performing a Man-in-the-Middle (MitM) attack, poisoning a CDN cache, or compromising a package mirror can substitute legitimate packages with malicious ones. Because mismatched packages are silently accepted, the resulting OCI images will contain unverified and potentially malicious code. This issue is addressed in version 1.2.7.
Affected products
- Chainguard apko < 1.2.7
Timeline
- 2026-04-23: patched: Version 1.2.7 released
- 2026-05-09: disclosed: Initial advisory publication