CVE-2026-13723

Summary

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.

Affected Software

Weaknesses

• CWE-22 Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
• CWE-59 Improper Link Resolution Before File Access ('Link Following')

ADP Enrichment

CVE Program Container

Additional References

• https://www.kb.cert.org/vuls/id/293714

CISA ADP Vulnrichment

• SSVC:
• Exploitation: none
  • Automatable: yes
  • Technical Impact: partial

References

• https://github.com/develar/app-builder
• http://kb.cert.org/vuls/id/293714
• https://github.com/develar/app-builder/pull/163

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