CVE-2026-25122 apko is vulnerable to unbounded resource consumption in expandapk.Split on attacker-controlled .apk streams
Attackers can cause resource exhaustion and denial of service in apko by providing malicious APK streams that trigger unbounded gzip inflation.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-25122?
CVE-2026-25122 is a medium-severity denial of service vulnerability in chainguard-dev apko, published on 4 Feb 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Official 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.
Which versions are affected by CVE-2026-25122?
3 open source packages ship an affected version, including chainguard.dev/apko. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
chainguard.dev/apko Go | From 0.14.8 | 1.1.0 |
chainguard.dev/apko Go | From 0.14.8 | 1.1.0 |
chainguard.dev/apko Go | From 0.14.8 | 1.1.0 |
Products include Chainguard Apko.
How do I fix CVE-2026-25122?
Upgrade chainguard.dev/apko to 1.1.0 or later.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-25122 being exploited?
There is no known exploitation of CVE-2026-25122 in the wild and no public exploit code.
Other vulnerabilities in chainguard-dev apko
Sources
Also known as GHSA-6p9p-q6wh-9j89, GO-2026-4406, MINI-ffr3-9whc-cr26.