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melange QEMU runner could write files outside workspace directory

High severity GitHub Reviewed Published Feb 3, 2026 in chainguard-dev/melange • Updated Feb 4, 2026

Package

gomod chainguard.dev/melange (Go)

Affected versions

>= 0.11.3, < 0.40.3

Patched versions

0.40.3

Description

An attacker who can influence the tar stream from a QEMU guest VM could write files outside the intended workspace directory on the host. The retrieveWorkspace function extracts tar entries without validating that paths stay within the workspace, allowing Path Traversal via ../ sequences.

Fix: Fixed in 6e243d0d. Merged in release.

Acknowledgements

melange thanks Oleh Konko from 1seal for discovering and reporting this issue.

References

@antitree antitree published to chainguard-dev/melange Feb 3, 2026
Published to the GitHub Advisory Database Feb 3, 2026
Reviewed Feb 3, 2026
Published by the National Vulnerability Database Feb 4, 2026
Last updated Feb 4, 2026

Severity

High

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Local
Attack complexity
Low
Privileges required
None
User interaction
Required
Scope
Changed
Confidentiality
None
Integrity
High
Availability
High

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:C/C:N/I:H/A:H

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(0th percentile)

Weaknesses

Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory. Learn more on MITRE.

CVE ID

CVE-2026-24843

GHSA ID

GHSA-qxx2-7h4c-83f4

Source code

Credits

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