apko /etc/passwd and /etc/group UID/GID truncation writes package-supplied entries as root
Summary
| CVE | CVE-2026-105768 |
|---|---|
| State | PUBLISHED |
| Assigner | chainguard |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-10-05 21:16:35 UTC |
| Updated | 2026-10-05 21:16:36 UTC |
| 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. |
Risk And Classification
Primary CVSS: v4.0 6.3 MEDIUM from 82cea9a6-e9e3-46fe-bdb0-3673de380178
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Problem Types: CWE-197 | CWE-197 CWE-197 Numeric Truncation Error
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 4.0 | 82cea9a6-e9e3-46fe-bdb0-3673de380178 | Secondary | 6.3 | MEDIUM | CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:L/SA:N/E:X/C... |
| 4.0 | CNA | CVSS | 6.3 | MEDIUM | CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:L/SA:N |
CVSS v4.0 Breakdown
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Chainguard-dev | Apko | affected 0.2.0 1.4.5 semver | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| github.com/chainguard-dev/apko/pull/2516 | 82cea9a6-e9e3-46fe-bdb0-3673de380178 | github.com | |
| github.com/chainguard-dev/apko/releases/tag/v1.4.5 | 82cea9a6-e9e3-46fe-bdb0-3673de380178 | github.com | |
| github.com/chainguard-dev/apko/commit/739e7ce3f675ffb232e16849b51ff93657... | 82cea9a6-e9e3-46fe-bdb0-3673de380178 | github.com | |
| github.com/chainguard-dev/apko/security/advisories/GHSA-rj6x-hwpv-vhvf | 82cea9a6-e9e3-46fe-bdb0-3673de380178 | github.com | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
Vendor Comments And Credit
Discovery Credit
CNA: Fernando (https://github.com/fthomasella) (en)
CNA: Jorge Lucangeli Obes (https://github.com/jlucangelio) (en)
CNA: Steve Beattie (https://github.com/stevebeattie) (en)
CNA: SunnyR (https://github.com/SunnyR) (en)
CNA: Chainguard (https://chainguard.dev) (en)
Additional Advisory Data
| Source | Time | Event |
|---|---|---|
| CNA | 2022-03-03T23:21:00.000Z | Truncating uint32 conversion introduced |
| CNA | 2026-09-21T22:49:00.000Z | Fix merged (chainguard-dev/apko#2516) |
| CNA | 2026-09-23T22:40:00.000Z | GHSA-rj6x-hwpv-vhvf published |
| CNA | 2026-09-28T00:51:00.000Z | apko v1.4.5 released |
Solutions
CNA: Upgrade to apko 1.4.5 or later, which rejects UID and GID values outside 0 to 4294967295 instead of truncating them. Images built with earlier versions from untrusted packages should be rebuilt.