Develar app-builder up to 4.2.0 Extraction Routine zipx.Unzip path traversal

Summaryinfo

A vulnerability classified as critical has been found in Develar app-builder up to 4.2.0. Affected is the function zipx.Unzip of the component Extraction Routine. This manipulation causes path traversal. The identification of this vulnerability is CVE-2026-13723. It is possible to initiate the attack remotely. There is no exploit available.

Detailsinfo

A vulnerability classified as critical was found in Develar app-builder up to 4.2.0. Affected by this vulnerability is the function zipx.Unzip of the component Extraction Routine. The manipulation with an unknown input leads to a path traversal vulnerability. The CWE definition for the vulnerability is CWE-22. 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. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

A vulnerability in the `zipx.Unzip` extraction routine of Develar's app-builder allows an attacker to overwrite arbitrary files on macOS APFS by exploiting a Unicode Normalization Collision combined with symlink following behavior. APFS treats certain Unicode equivalent filenames as identical (e.g., ß ↔ ss), while app builder performs no canonical normalization before validating or writing paths. As a result, a crafted ZIP archive containing: • a symlink entry named ss pointing to a target file, and • a regular file named ß containing attacker controlled data, will cause the second write to follow the symlink and overwrite the target file.

The advisory is shared at github.com. This vulnerability is known as CVE-2026-13723 since 06/29/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. It demands that the victim is doing some kind of user interaction. Technical details are known, but no exploit is available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 07/29/2026). MITRE ATT&CK project uses the attack technique T1006 for this issue.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

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Productinfo

Vendor

• Develar

Name

• app-builder

Version

• 4.0
• 4.1
• 4.2.0

CPE 2.3info

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CPE 2.2info

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