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CVE-2026-24843VulnerabilityPublished

CVE-2026-24843: chainguard-dev melange · Path Traversal

Affects chainguard-dev melangeSource CVE Database V5

0

Not known to be exploited · CVSS 8.2 High : upgrade to 0.40.3 soon.

Data as of 25 Oct 2026, 19:02 UTC

CVSS 3.1 base score
8.2High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.1% chance of exploitation in 30 days – higher than 8% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 0.40.3
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:C/C:N/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 4 Feb 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 2026-10-25.

What to do

Upgrade melange and chainguard-dev/melange to 0.40.3.

Affected software

ProductAffectedFixed in
chainguard-devmelangeAffected
  • >=0.11.3 <0.40.3
Fixed in
  • 0.40.3
GitHubchainguard-dev/melangepkg:github/chainguard-dev/melangeOther threatsAffected
  • <0.40.3 >=0.11.3
Fixed in
  • 0.40.3

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

The primary mitigation is to upgrade melange to version 0.40.3 or later, where the vulnerability is patched. Organizations should audit their build environments to identify any instances of melange within the affected version range. Restricting and monitoring access to QEMU guest VMs is critical to prevent unauthorized manipulation of tar streams. Implement strict controls on who can influence build inputs and tar archives. Employ runtime monitoring to detect anomalous file writes outside expected directories during builds. Consider sandboxing or isolating build hosts to limit the impact of potential escapes. Additionally, validate all inputs and outputs in build pipelines and use integrity verification mechanisms on build artifacts. Regularly review and update CI/CD pipeline security policies to incorporate lessons from this vulnerability.

Description

CVE-2026-24843 is a high-severity path traversal vulnerability in chainguard-dev's melange tool versions 0.11.3 up to before 0.40.3. It allows an attacker who can influence the tar stream from a QEMU guest VM to write files outside the intended workspace on the host system. This occurs because the retrieveWorkspace function does not properly validate tar entry paths, enabling directory traversal via '.. /' sequences. Exploitation requires local access to influence the tar stream and some user interaction, but no privileges are needed. The vulnerability can lead to integrity and availability impacts by overwriting or creating arbitrary files on the host.

References

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