VulnerabilityPublished 24 Apr 2026

CVE-2026-29051: chainguard-dev melange · Path Traversal

Affects chainguard-dev melangeSource CVE Database V5

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Not known to be exploited · CVSS 4.4 Medium : upgrade to 0.43.4 when convenient.

Data as of 30 Oct 2026, 06:59 UTC

CVSS 3.1 base score

4.4Medium

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.1% chance of exploitation in 30 days – higher than 6% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 0.43.4

CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:L

Attack Vector: Local
Attack Complexity: Low
Privileges Required: None
User Interaction: Required
Scope: Unchanged
Confidentiality: None
Integrity: Low
Availability: Low

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Local: The vulnerable component is not bound to the network stack and the attacker’s path is via read/write/execute capabilities. Either: the attacker exploits the vulnerability by accessing the target system locally (e.g., keyboard, console), or remotely (e.g., SSH); or the attacker relies on User Interaction by another person to perform actions required to exploit the vulnerability (e.g., tricking a legitimate user into opening a malicious document).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: Required: Successful exploitation of this vulnerability requires a user to take some action before the vulnerability can be exploited.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: None: There is no loss of confidentiality within the impacted component.
Integrity: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact on the impacted component.
Availability: Low: Performance is reduced or there are interruptions in resource availability. Even if repeated exploitation of the vulnerability is possible, the attacker does not have the ability to completely deny service to legitimate users. The resources in the impacted component are either partially available all of the time, or fully available only some of the time, but overall there is no direct, serious consequence to the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 24 Apr 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by 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 29 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade melange and chainguard-dev/melange to 0.43.4.

Affected software

Product	Affected	Fixed in
chainguard-devmelange	Affected >=0.32.0 <0.43.4	Fixed in 0.43.4
GitHubchainguard-dev/melange`pkg:github/chainguard-dev/melange`Other threats	Affected <0.43.4 >=0.32.0	Fixed in 0.43.4

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

AI-suggested

The vulnerability is fixed in melange version 0.43.4 by validating input values before path construction. Users should upgrade to version 0.43.4 or later. As a workaround, do not use the --persist-lint-results flag when linting or building APKs with untrusted .PKGINFO contents. Running melange as a low-privileged user and restricting write permissions to an isolated directory further limits potential impact. Patch status is not explicitly stated in vendor advisory content, but the fix is included in version 0.43.4.

Description

CVE-2026-29051 is a path traversal vulnerability in chainguard-dev's melange versions from 0.32.0 up to but not including 0.43.4. When the --persist-lint-results flag is used, melange constructs output file paths from unvalidated values in the APK's . PKGINFO file, allowing an attacker supplying a malicious APK to cause melange to write JSON lint reports to arbitrary filesystem locations. This can overwrite existing JSON files but does not allow direct code execution. The vulnerability only affects deployments explicitly using the --persist-lint-results option, which is off by default. The issue is fixed in version 0.

Impact

An attacker able to supply APKs to a melange lint/build pipeline that uses the --persist-lint-results flag can cause arbitrary file write of JSON lint reports to paths outside the intended output directory. This can overwrite existing JSON files, potentially disrupting build or lint artifacts. There is no direct impact on confidentiality or code execution. The impact is limited to integrity and availability of JSON lint report files. The vulnerability does not affect default melange usage since the flag is off by default.

CWE-22Improper Limitation of a Pathname to a Restricted Directory (Path Traversal) (opens in a new tab)
Base weaknessLikelihood of exploit: HighCWE Top 25 (2025): #6OWASP Top 10 A01:2025: Broken Access Control (opens in a new tab)
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.
Implementation · Input Validation
Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
Architecture and Design
For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks…
Implementation · Input Validation
Inputs should be decoded and canonicalized to the application's current internal representation before being validated (CWE-180). Make sure that the application does not decode the same input twice (CWE-174).
OWASP Cheat Sheets
Authorization (opens in a new tab)
OWASP ASVS 4.0.3
V12.3.1 (opens in a new tab)
Attack patterns
Path Traversal (opens in a new tab)
Using Slashes and URL Encoding Combined to Bypass Validation Logic (opens in a new tab)
Manipulating Web Input to File System Calls (opens in a new tab)
Using Escaped Slashes in Alternate Encoding (opens in a new tab)
Using Slashes in Alternate Encoding (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 1 May 2026, 20:48 UTC

WeaknessesCWE-22

Technical details

References

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