All vulnerabilities
CVE-2026-105768GHSA-rj6x-hwpv-vhvf

apko /etc/passwd and /etc/group UID/GID truncation writes package-supplied entries as root

chainguard-dev apko
CVSS
6.3Medium
ExploitationNo known exploitationNot in CISA KEV, which does not prove it is unexploitedCISA KEV
Exploit odds (EPSS)0.30%Chance of exploitation activity in the next 30 days, higher than 21% of CVEs. Scored 23 Oct 2026FIRST EPSS
Fixed in1.4.5Fixed versionCVE List
Published5 Oct 2026Updated 6 Oct 2026CVE List

What fixes it

  • 1.4.5apkoCVE List
  • 1.4.5chainguard.dev/apko, goGitHubgo get chainguard.dev/apko@v1.4.5

A fixed version on one release line is not the upgrade target for every line. Check your exact version and any vendor backports.

Description

apko allows users to build and publish OCI container images built from apk packages. From version 0.2.0 to before version 1.4.5, UserEntry.Parse and GroupEntry.Parse in pkg/passwd read the UID and GID fields of /etc/passwd and /etc/group entries with strconv.Atoi and convert them to uint32 without a range check. On 64-bit platforms an out-of-range value such as 4294967296 (2^32) is truncated to 0, and negative values wrap. Because apko parses the passwd and group entries supplied by the packages it installs and writes them back into the image, an attacker who controls a package installed into the image can ship an entry that appears to declare an unprivileged UID or GID but is written into the built image as UID 0 or GID 0 (root). The truncated UID is also used when resolving the image's run-as user. This issue has been fixed in version 1.4.5.

Text from CVE List

Affected versions 2

  • apkoaffected: 0.2.0 before 1.4.5CVE List
  • chainguard.dev/apko, go>= 0.2.0, < 1.4.5GitHub

References 4