Apko allows builders to incorporate apk packages into container images. From version 0.14.8 up to (but not including) 1.1.0, the expandapk.Split function drains the first gzip stream of an APK archive without any explicit limit on uncompressed data or inflation ratio. An attacker can supply a crafted APK stream that inflates to a very large size, forcing the process to perform extensive CPU‑bound decompression. This results in significant resource exhaustion, causing timeouts or slowing the build process and thereby impacting availability.

The vulnerability affects Chainguard Development’s open‑source apko tool. All releases from 0.14.8 through 1.0.x are impacted, while the fix is included in version 1.1.0 and later.

The CVSS score of 5.5 indicates a moderate severity, and the EPSS score of less than 1% suggests that exploitation is currently unlikely. The vulnerability is not listed in the CISA KEV catalog. The most probable exploitation path involves an entity that controls the input to the apko build process; if an attacker can supply a malicious APK archive, they can induce the large‑scale decompression and trigger resource starvation. Because the attack requires the attacker’s input to be processed, the threat is more likely in contexts where untrusted packages are accepted or when building images from external sources.