CVE-2026-25145VulnerabilityPublished 4 Feb 2026

CVE-2026-25145: chainguard-dev melange · Path Traversal

Affects chainguard-dev melangeSource CVE Database V5

Not known to be exploited · CVSS 5.5 Medium : upgrade to 0.40.3 when convenient.

Data as of 26 Oct 2026, 06:26 UTC

CVSS 3.1 base score

5.5Medium

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

EPSS: 0.1% chance of exploitation in 30 days – higher than 9% 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:U/C:H/I:N/A:N

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

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: High: There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 4 Feb 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: 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 2026-10-26.

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.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC 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 0.40.3.

Affected software

Product	Affected	Fixed in
chainguard-devmelange	Affected >=0.14.0 <0.40.3	Fixed in 0.40.3
GitHubchainguard-dev/melange`pkg:github/chainguard-dev/melange`Other threats	Affected <0.40.3 >=0.14.0	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

1. Upgrade melange to version 0.40.3 or later, where the path traversal vulnerability is patched. 2. Restrict who can influence melange configuration files, especially in CI/CD pipelines—limit pull request merges and build triggers to trusted users. 3. Implement strict validation and sanitization of all inputs in build configurations, particularly paths specifying license files. 4. Isolate build environments using containerization or sandboxing to limit access to host filesystem outside the workspace. 5. Monitor build artifacts and SBOM outputs for unexpected or suspicious license text content that may indicate exfiltration attempts. 6. Employ file integrity monitoring on build hosts to detect unauthorized file reads or access patterns consistent with path traversal. 7. Review and audit existing SBOMs generated by affected melange versions for embedded sensitive data and rotate any potentially exposed credentials. 8. Educate developers and CI administrators about the risks of accepting untrusted configuration inputs and enforce code review policies accordingly.

Description

CVE-2026-25145 is a medium severity path traversal vulnerability in chainguard-dev's melange tool versions 0.14.0 up to before 0.40.3. It allows an attacker who can influence melange configuration files—such as via pull request-driven CI or build-as-a-service environments—to read arbitrary files on the host system. The vulnerability arises from insufficient validation of license file paths in the LicensingInfos function, enabling traversal outside the intended workspace directory. The contents of these files can then be embedded into the generated SBOM, facilitating exfiltration of sensitive data through build artifacts. This issue does not require privileges but does require user interaction to trigger a build with a malicious configuration. The flaw has been patched in version 0.

Impact

For European organizations, this vulnerability poses a significant risk of sensitive data leakage from build environments, especially those employing melange in CI/CD pipelines or build-as-a-service platforms. Attackers who can submit or influence build configurations—such as external contributors in open-source projects or third-party developers—could exploit this flaw to access confidential files on build hosts, including credentials, proprietary source code, or internal documentation. The exfiltrated data embedded in SBOMs may then be inadvertently shared or exposed, increasing the risk of intellectual property theft or compliance violations under regulations like GDPR. While the vulnerability does not directly affect system integrity or availability, the confidentiality breach could lead to reputational damage, regulatory penalties, and further targeted attacks. Organizations relying on melange for package builds should consider the sensitivity of their build environments and the trustworthiness of contributors to mitigate exploitation risks.

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 12 Feb 2026, 07:42 UTC

WeaknessesCWE-22

Technical details

References

Community reviews

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