melange: Incomplete package integrity verification allows data section substitution

published 2026-07-10 3 mo ago modified 2026-09-30 39 d ago also EUVD-2026-76767 , GHSA-fpg8-7664-jc5q , GO-2026-5968

cvss: 8.3; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.2%; EPSS 0.2% chance of exploitation in 30 days, percentile 4%
public exploits: 0; none known

melange allows users to build apk packages using declarative pipelines. Apko prior to version 1.2.9, corresponding to melange prior to version 0.50.4, verified the control section hash (`.PKGINFO` etc.) against the signed `APKINDEX`, but never verified the data section hash (the actual package files that get installed). An attacker who could compromise a mirror, poison a cache, or MITM a package fetch could substitute arbitrary file contents while the control hash check still passed. Apko version 1.2.9 and melange version 0.50.4 contain a fix.

Patch / fix

fixed in 4 distros 1

go chainguard.dev/apko 1.2.9
go chainguard.dev/melange 0.50.4
chainguard melange 0.50.4
chainguard apko 1.2.9

apko openSUSE Tumbleweed 1.4.4-1.1
govulncheck-vulndb openSUSE Leap 16.0 0.0.20260723T184607-160000.1.1

opensuse advisories openSUSE-SU-2026:11829-1 openSUSE-SU-2026:21483-1

CISA SSVC

Exploitation: none
Automatable: no
Technical impact: total
Assessed: 55 d ago (2026-09-14)

Exploit prediction

0.15% chance of exploitation in the next 30 days, higher than 4% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	3.1	8.3	CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:H
GitHub	3.1	8.3	CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:H

Affected packages

ecosystem	package	affected	fixed in
go	chainguard.dev/apko	<1.2.9	1.2.9
go	chainguard.dev/melange	<0.50.4	0.50.4

Affected products

chainguard-dev melange
chainguard-dev apko

Classification

Weakness

CWE-354 Improper Validation of Integrity Check Value
CWE-345 Insufficient Verification of Data Authenticity

References

github.com /chainguard-dev/melange/security/advisories/GHSA-fpg8-7664-jc5q
web, advisory
github.com /chainguard-dev/melange
package

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.

Summary