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HIGH severity

apko doesn't verify downloaded apk packages against APKINDEX checksum (package substitution possible)GHSA-hcwr-pq9g-rq3m

HIGHFix: chainguard-dev/apko@a118c3d

GHSA-hcwr-pq9g-rq3m is a high-severity (CVSS 7.5) CWE-345 vulnerability in chainguard.dev/apko. A fix is available for chainguard.dev/apko — see the affected versions and patch details below.

Also known asCVE-2026-42575GO-2026-5422
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Nov 6, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

  • CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
  • CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for GHSA-hcwr-pq9g-rq3m.

EPSS Exploitation Probability

via FIRST.org ↗
0.2%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs5th percentile — riskier than 5% of all scored CVEsHighest risk
0.00%0.24%0.49%0.73%0.0%0.2%Jun 26Sep 26Nov 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected
🐹chainguard.dev/apko

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.

Description

apko verifies the signature on APKINDEX.tar.gz but never compares individually downloaded .apk packages against the checksum recorded in the signed index. The checksum is parsed and available via ChecksumString(), and the downloaded package control hash is computed, but the two values are never compared in getPackageImpl(). Mismatched packages are silently accepted. An attacker who can substitute download responses (compromised mirror, HTTP repository, poisoned CDN cache) can install arbitrary packages into built images.

Fix: No fix available yet.

Acknowledgements

apko thanks Oleh Konko from 1seal for discovering and reporting this issue.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
🐹Gochainguard.dev/apkoall versions1.2.7go get chainguard.dev/apko@v1.2.7

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for chainguard.dev/apko, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update chainguard.dev/apko to 1.2.7 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-hcwr-pq9g-rq3m is resolved across your whole dependency graph.

  3. Workarounds

    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Frequently Asked Questions

apko verifies the signature on `APKINDEX.tar.gz` but never compares individually downloaded `.apk` packages against the checksum recorded in the signed index. The checksum is parsed and available via `ChecksumString()`, and the downloaded package control hash is computed, but the two values are never compared in `getPackageImpl()`. Mismatched packages are silently accepted. An attacker who can substitute download responses (compromised mirror, HTTP repository, poisoned CDN cache) can install arbitrary packages into built images. **Fix:** No fix available yet. **Acknowledgements** apko thank
O3 Security · Impact-Aware SCA

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