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Medium severity4.4NVD Advisory· Published Apr 24, 2026· Updated Apr 27, 2026

CVE-2026-29051

CVE-2026-29051

Description

melange allows users to build apk packages using declarative pipelines. Starting in version 0.32.0 and prior to version 0.43.4, melange lint --persist-lint-results (opt-in flag, also usable via melange build --persist-lint-results) constructs output file paths by joining --out-dir with the arch and pkgname values read from the .PKGINFO control file of the APK being linted. In affected versions these values were not validated for path separators or .. sequences, so an attacker who can supply an APK to a melange-based lint/build pipeline (e.g. CI that lints third-party APKs, or build-as-a-service) could cause melange to write lint-<pkgname>-<pkgver>-r<epoch>.json to an arbitrary .json path reachable by the melange process. The written file is a JSON lint report whose content is partially attacker-influenced. There is no direct code-execution path, but the write can clobber other JSON artifacts on the filesystem. The issue only affects deployments that explicitly pass --persist-lint-results; the flag is off by default. The issue is fixed in melange v0.43.4 by validating arch and pkgname for .., /, and filepath.Separator before path construction in pkg/linter/results.go (commit 84f3b45). As a workaround, do not pass --persist-lint-results when linting or building APKs whose .PKGINFO contents are not fully trusted. Running melange as a low-privileged user and confining writes to an isolated directory also limits impact.

Affected packages

Versions sourced from the GitHub Security Advisory.

PackageAffected versionsPatched versions
chainguard.dev/melangeGo
>= 0.32.0, < 0.43.40.43.4

Affected products

1
  • Chainguard/Melange
    cpe:2.3:a:chainguard:melange:*:*:*:*:*:go:*:*
    Range: >=0.32.0,<0.43.4

Patches

1
84f3b450ce6e

Merge commit from fork

https://github.com/chainguard-dev/melangeEvan GiblerFeb 27, 2026via ghsa
commit
1 file changed · +18 −0
  • pkg/linter/results.go+18 −0 modified
    @@ -20,13 +20,22 @@ import (
 	"fmt"
 	"os"
 	"path/filepath"
+	"strings"
 
 	"github.com/chainguard-dev/clog"
 
 	"chainguard.dev/melange/pkg/config"
 	"chainguard.dev/melange/pkg/linter/types"
 )
 
+// containsPathTraversal checks if a string contains path traversal sequences
+// or path separators that could be used to escape the intended directory.
+func containsPathTraversal(s string) bool {
+	return strings.Contains(s, "..") ||
+		strings.Contains(s, string(filepath.Separator)) ||
+		strings.Contains(s, "/")
+}
+
 // saveLintResults saves the lint results to JSON files in the packages directory
 func saveLintResults(ctx context.Context, cfg *config.Configuration, results map[string]*types.PackageLintResults, outputDir, arch string) error {
 	log := clog.FromContext(ctx)
@@ -37,6 +46,11 @@ func saveLintResults(ctx context.Context, cfg *config.Configuration, results map
 		return nil
 	}
 
+	// Validate arch to prevent path traversal
+	if containsPathTraversal(arch) {
+		return fmt.Errorf("invalid arch %q: contains path traversal sequence", arch)
+	}
+
 	// Ensure the package directory exists
 	packageDir := filepath.Join(outputDir, arch)
 	if err := os.MkdirAll(packageDir, 0o755); err != nil {
@@ -45,6 +59,10 @@ func saveLintResults(ctx context.Context, cfg *config.Configuration, results map
 
 	// Save results for each package
 	for pkgName, pkgResults := range results {
+		// Validate pkgName to prevent path traversal
+		if containsPathTraversal(pkgName) {
+			return fmt.Errorf("invalid package name %q: contains path traversal sequence", pkgName)
+		}
 		// Generate the filename: lint-{packagename}-{version}-r{epoch}.json
 		filename := fmt.Sprintf("lint-%s-%s-r%d.json", pkgName, cfg.Package.Version, cfg.Package.Epoch)
 		filepath := filepath.Join(packageDir, filename)

Vulnerability mechanics

Generated by null/stub on May 9, 2026. Inputs: CWE entries + fix-commit diffs from this CVE's patches. Citations validated against bundle.

References

4

News mentions

1