CVE-2026-25122: apko is vulnerable to unbounded resource consumption in expandapk.Split on attacker-controlled .apk streams

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.1% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-02-04 · updated 2026-06-17
Weakness: CWE-400

Description

apko allows users to build and publish OCI container images built from apk packages. From version 0.14.8 to before 1.1.0, expandapk.Split drains the first gzip stream of an APK archive via io.Copy(io.Discard, gzi) without explicit bounds. With an attacker-controlled input stream, this can force large gzip inflation work and lead to resource exhaustion (availability impact). The Split function reads the first tar header, then drains the remainder of the gzip stream by reading from the gzip reader directly without any maximum uncompressed byte limit or inflate-ratio cap. A caller that parses attacker-controlled APK streams may be forced to spend excessive CPU time inflating gzip data, leading to timeouts or process slowdown. This issue has been patched in version 1.1.0.

Affected products

chainguard-dev apko: from 0.14.8 before 1.1.0 — fixed in 1.1.0

How to fix

Upgrade to a fixed version: chainguard-dev apko 1.1.0. Check the vendor advisory for mitigations.

References

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