CVE-2026-105768 apko /etc/passwd and /etc/group UID/GID truncation writes package-supplied entries as root
Attackers can force package-supplied entries to run as root by exploiting UID/GID truncation in apko, leading to privilege escalation in built images.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-105768?
CVE-2026-105768 is a medium-severity vulnerability in chainguard-dev apko, published on 5 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Weakness: CWE-197
Which versions are affected by CVE-2026-105768?
How do I fix CVE-2026-105768?
No fix has been published for CVE-2026-105768 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-105768 being exploited?
There is no known exploitation of CVE-2026-105768 in the wild and no public exploit code.
Sources
Also known as GHSA-rj6x-hwpv-vhvf.