apko doesn't verify downloaded apk packages against APKINDEX checksum (package substitution possible)

published 2026-05-04 6 mo ago modified 2026-09-10 1 mo ago also EUVD-2026-28933 , GHSA-hcwr-pq9g-rq3m , GO-2026-5422

cvss: 7.5; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.2%; EPSS 0.2% chance of exploitation in 30 days, percentile 5%
public exploits: 0; none known

apko allows users to build and publish OCI container images built from apk packages. Prior to version 1.2.7, 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. This issue has been patched in version 1.2.7.

Patch / fix

fixed in 2 distros 1 links 2

go chainguard.dev/apko 1.2.7
chainguard apko 1.2.7

govulncheck-vulndb openSUSE Leap 16.0 0.0.20260723T184607-160000.1.1

opensuse advisories openSUSE-SU-2026:21483-1

github.com/chainguard-dev/apko@a118c3d commit
github.com/chainguard-dev/apko/releases/tag/v1.2.7 release

CISA SSVC

Exploitation: none
Automatable: yes
Technical impact: partial
Assessed: 5 mo ago (2026-05-13)

Exploit prediction

0.16% chance of exploitation in the next 30 days, higher than 5% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	3.1	7.5	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
GitHub	3.1	7.5	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Affected packages

ecosystem	package	affected	fixed in
go	chainguard.dev/apko	<1.2.7	1.2.7

Affected products

chainguard-dev apko

Classification

Weakness

CWE-345 Insufficient Verification of Data Authenticity
CWE-494 Download of Code Without Integrity Check

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.

Summary