GHSA-qq3r-w4hj-gjp6Published

apko dirFS has a symlink-following path traversal that allows multiple entry points to escape the build root

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cve-program · CVE-2026-42574

Published

apko allows users to build and publish OCI container images built from apk packages. From version 0.14.8 to before version 1.2.5, a crafted .apk could install a TypeSymlink tar entry whose target pointed outside the build root, and a subsequent directory-creation or file-write entry in the same or later archive could traverse that symlink to reach host paths the build user could write to. This issue has been patched in version 1.2.5.

Source published: 9 May 2026 19:24:48 UTC
Source modified: 11 May 2026 17:11:40 UTC
Saved here: 23 Oct 2026 15:48:27 UTC
Source terms: CVE Program Terms of Use

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CVSS 3.1 · 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

euvd · EUVD-2026-28932

Published

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EUVD source date text has no stated timezone and is retained without inventing a UTC instant. Related bulletin membership is not an alias, common cause or applicability claim. A missing vector with a zero score is treated as unrated. Complete vendor/product and underlying source evidence remains in the original JSON.

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datePublished: May 9, 2026, 7:24:48 PM

dateUpdated: May 11, 2026, 5:11:40 PM

Source published: May 9, 2026, 7:24:48 PM (timezone not stated)
Source modified: May 11, 2026, 5:11:40 PM (timezone not stated)
Saved here: 13 Nov 2026 12:04:05 UTC
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EUVD CVSS 3.1 · 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

nvd · CVE-2026-42574

Published

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NVD analysis and CPE criteria are source context, not proof that a package or your environment is affected. Complete affected data, logical configurations and SSVC are retained in the original JSON.

Source analysis status: Deferred

Weakness classifications: CWE-22 · CWE-59

Original publisher date fields

published: 2026-05-09T20:16:29.420

lastModified: 2026-07-24T21:10:00.143

Source published: 9 May 2026 20:16:29 UTC
Source modified: 24 Jul 2026 21:10:00 UTC
Saved here: 25 Oct 2026 10:17:15 UTC
Source terms: NIST NVD usage terms; underlying source attribution retained

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CVSS 3.1 · [email protected] · Secondary · 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

osv · GHSA-qq3r-w4hj-gjp6

Published

### Impact A crafted `.apk` could install a `TypeSymlink` tar entry whose target pointed outside the build root, and a subsequent directory-creation or file-write entry in the same or later archive could traverse that symlink to reach host paths the build user could write to. The root cause was the `sanitizePath` helper in `pkg/apk/fs/rwosfs.go`, which rejected only lexical `..` traversal and did not resolve or refuse symlinks. Every disk-backed `DirFS` method that handed its caller-supplied path to a symlink-following stdlib call — `ReadFile`, `WriteFile`, `Chmod`, `Chown`, `Chtimes`, `MkdirAll`, `Mkdir`, and `Mknod` — was affected. The reachable primitive from a malicious APK during tar extraction is the `MkdirAll` / `Mkdir` / `WriteFile` chain via `apko build-cpio` and disk-backed consumers such as `melange`; the remaining sinks are reachable by direct callers of the `pkg/apk/fs` package. The in-memory `tarfs` install path used by `apko build`, `apko publish`, and `apko build-minirootfs` is not affected. ### Patches Fixed in apko **v1.2.5** by [#2187](https://github.com/chainguard-dev/apko/pull/2187) / commit [f5a96e1](https://github.com/chainguard-dev/apko/commit/f5a96e1299ac81c7ea9441705ec467688086f442), which scopes all `DirFS` operations through a Go 1.24 `*os.Root`. The `sanitizePath` helper has been removed; `*os.Root` refuses traversal via `..`, absolute-target symlinks, relative-target symlinks, and hardlinks by construction. Regression tests in `pkg/apk/apk/path_traversal_test.go` cover each composite primitive. ### Workarounds No complete workaround. Operators running pre-1.2.5 apko (or downstream tools such as melange that embed pre-1.2.5 `pkg/apk/fs`) should upgrade. Consuming only APKs from trusted, signed sources reduces but does not eliminate exposure. ### Resources - https://github.com/chainguard-dev/apko/pull/2187 - https://github.com/chainguard-dev/apko/commit/f5a96e1299ac81c7ea9441705ec467688086f442 - https://github.com/chainguard-dev/apko/releases/tag/v1.2.5 - Related: GHSA-5g94-c2wx-8pxw (CVE-2026-25121) — prior lexical `..` traversal fix ### Credits apko thanks Oleh Konko ([@1seal](https://github.com/1seal) from [1seal.org](https://1seal.org/)) for the initial report of the symlink-escape class, and to [@Xh081iX](https://github.com/Xh081iX) for a follow-up set of reports covering additional reachable primitives (`ReadFile`, `Chmod`/`Chown`, `Mknod`, `MkdirAll`/`Mkdir`) that shaped the comprehensive fix.

Source published: 4 May 2026 21:26:47 UTC
Source modified: 10 Sep 2026 03:51:06 UTC
Saved here: 24 Oct 2026 13:19:41 UTC
Source terms: GitHub Advisory Database · CC-BY-4.0

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Source: osv · GitHub Advisory Database · CC-BY-4.0. The publisher's wording is preserved. ChangeIntel groups the information and labels changes. The JSON record includes additional source fields.

CVSS_V3 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Publisher rating · HIGH

osv · GO-2026-5589

Published

apko dirFS has a symlink-following path traversal that allows multiple entry points to escape the build root in chainguard.dev/apko

Source published: 25 Jun 2026 22:34:34 UTC
Source modified: 25 Jun 2026 23:01:32 UTC
Saved here: 24 Oct 2026 13:19:41 UTC
Source terms: OSV · upstream source license applies

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Source: osv · OSV · upstream source license applies. The publisher's wording is preserved. ChangeIntel groups the information and labels changes. The JSON record includes additional source fields.