Chainguard apko up to 1.4.4 Passwd Parsing pkg/passwd UserEntry.Parse/GroupEntry.Parse UID/GID integer overflow

Summaryinfo

A vulnerability labeled as problematic has been found in Chainguard apko up to 1.4.4. This affects the function UserEntry.Parse/GroupEntry.Parse of the file pkg/passwd of the component Passwd Parsing. Such manipulation of the argument UID/GID leads to integer overflow. This vulnerability is uniquely identified as CVE-2026-105768. The attack can be launched remotely. No exploit exists. The affected component should be upgraded.

Detailsinfo

A vulnerability, which was classified as problematic, has been found in Chainguard apko up to 1.4.4. Affected by this issue is the function UserEntry.Parse/GroupEntry.Parse of the file pkg/passwd of the component Passwd Parsing. The manipulation of the argument UID/GID with an unknown input leads to a integer overflow vulnerability. Using CWE to declare the problem leads to CWE-190. The product performs a calculation that can produce an integer overflow or wraparound, when the logic assumes that the resulting value will always be larger than the original value. This can introduce other weaknesses when the calculation is used for resource management or execution control. Impacted is integrity, and availability. CVE summarizes:

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.

The advisory is available at github.com. This vulnerability is handled as CVE-2026-105768 since 10/05/2026. The exploitation is known to be easy. The attack may be launched remotely. Additional levels of successful authentication are required for exploitation. Successful exploitation requires user interaction by the victim. Technical details are known, but there is no available exploit.

Upgrading to version 1.4.5 eliminates this vulnerability.

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Productinfo

Vendor

• Chainguard

Name

• apko

Version

• 1.4.0
• 1.4.1
• 1.4.2
• 1.4.3
• 1.4.4

CPE 2.3info

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