CVE-2026-54174: 
Wolfi Análisis y mitigación de vulnerabilidades

CVE-2026-54174 is a incomplete package integrity verification vulnerability in Apko and Melange (Chainguard) that allows an attacker to substitute arbitrary package file contents during installation while bypassing integrity checks. Apko verified the control section hash (.PKGINFO, etc.) against the signed APKINDEX, but never verified the data section hash covering the actual package files installed on the system. This flaw affects chainguard.dev/apko versions before 1.2.9 and chainguard.dev/melange versions before 0.50.4. It was first published on June 3, 2026, and added to the GitHub Advisory Database on July 10, 2026, with a CVSS v3.1 base score of 8.3 (High) (GitHub Advisory, Melange Advisory).

The root cause is classified under CWE-345 (Insufficient Verification of Data Authenticity) and CWE-354 (Improper Validation of Integrity Check Value). APK packages consist of two sections: a control section (containing metadata like .PKGINFO) and a data section (containing the actual files to be installed). Apko validated the control section hash against the signed APKINDEX, but omitted validation of the data section hash, meaning the cryptographic integrity guarantee did not extend to the files actually written to disk. An attacker positioned to compromise a package mirror, poison a local or CDN cache, or perform a man-in-the-middle attack on a package fetch could replace the data section with arbitrary malicious content while the control hash check continued to pass (GitHub Advisory).

Successful exploitation allows an unauthenticated attacker to install arbitrary malicious files on target systems under the guise of legitimate, integrity-verified packages. This results in high confidentiality, integrity, and availability impact with a changed scope, meaning the compromise can extend beyond the package manager itself to the broader system environment. Malicious files installed this way could include backdoors, credential stealers, or destructive payloads, enabling persistent access, lateral movement, or full system compromise (GitHub Advisory, Melange Advisory).

1. Reconnaissance: Identify target environments using Apko or Melange versions prior to the patched releases (chainguard.dev/apko < 1.2.9 or chainguard.dev/melange < 0.50.4) that fetch packages from APK mirrors.
2. Establish attacker position: Gain the ability to intercept or tamper with package fetches via one of: compromising an upstream APK mirror, poisoning a local or CDN package cache, or performing a man-in-the-middle attack on the network path between the build system and the mirror.
3. Craft malicious package: Prepare a modified APK archive where the control section (.PKGINFO, etc.) and its hash remain intact and match the signed APKINDEX entry, but the data section (actual installed files) is replaced with malicious content (e.g., a backdoor binary or malicious script).
4. Serve tampered package: Deliver the crafted package in response to a legitimate package fetch request from the vulnerable Apko/Melange instance.
5. Bypass integrity check: The vulnerable Apko version validates only the control section hash, which passes. The data section hash is never checked, so the tampered files are accepted as legitimate.
6. Achieve code execution: The malicious files from the data section are installed on the target system, enabling arbitrary code execution, persistence, or further compromise (GitHub Advisory).

• Network: Unexpected or anomalous responses from APK mirror endpoints during package fetches; TLS certificate anomalies or unexpected redirects on package download requests.
• File System: Installed package files whose checksums do not match expected values from the upstream package source; unexpected binaries or scripts in directories populated by APK package installation.
• Logs: Build or CI/CD logs showing package fetches from unfamiliar or unexpected mirror URLs; warnings or errors from integrity verification tools run post-installation.
• Process: Unexpected processes spawned shortly after package installation steps in build pipelines; unusual outbound network connections from newly installed package binaries.

Upgrade chainguard.dev/apko to version 1.2.9 or later and chainguard.dev/melange to version 0.50.4 or later, which add verification of the data section hash (GitHub Advisory, Melange Advisory). As interim mitigations, ensure packages are fetched exclusively over TLS from trusted, authenticated mirrors, and consider pinning package sources to known-good mirrors. Implement additional post-installation verification mechanisms (e.g., comparing installed file hashes against a trusted manifest) and monitor package distribution infrastructure for signs of cache poisoning or MITM activity.