CVE-2026-81690: verify-usb before 1.4.9 Symlink Directory Traversal Code Execution
openssl-encrypt (pip package) before 1.4.9 contains a symlink-following flaw in its verify-usb v2 added-file allowlist scan. The scan enumerated the drive with rglob(), which in CPython does not descend into symlinked directories and treats the symlink as an ordinary directory, while ONOFOLLOW on the hash side binds only the final path component. An evil-maid attacker with physical access to the removable drive could replace a tool-tree directory with a symlink to a copy containing byte-identical files plus a planted pycache/.pyc file (which CPython loads in preference to recompiling the clean .py). The planted file is never enumerated, addedfiles stays 0, and verify-usb reports PASSED, resulting in code execution when the victim runs the portable install. Fixed in 1.4.9 (affects both 1.4.x and 1.5.x lines).
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
openssl-encrypt (pip package)to a version that resolves this vulnerability.Fixed in 1.4.9Patch verify-usb before 1.4.9 Symlink Directory Traversal Code Execution - Upgrade
Upgrade
openssl-encrypt (pip package)to a version that resolves this vulnerability.Patch verify-usb v2 added-file allowlist scan
Event History
Frequently Asked Questions
Who is realistically exposed to this issue?
Users of the openssl-encrypt pip package who use the verify-usb v2 scan on a portable installation stored on removable media are exposed if an attacker can physically access and modify that drive. The issue affects versions before 1.4.9 in both the 1.4.x and 1.5.x release lines.
What must an attacker do to exploit it?
An attacker needs physical access to the removable drive and must replace a tool-tree directory with a symlink to an attacker-controlled copy. That copy retains byte-identical expected files while adding a planted __pycache__/*.pyc file that is not detected by the allowlist scan.
Does successful verification mean the portable install is safe?
No. On affected versions, verify-usb can report PASSED even when the symlinked directory contains the planted Python bytecode file. Code execution occurs when the victim subsequently runs the portable installation.
What is the remediation?
Upgrade openssl-encrypt to version 1.4.9 or later. If upgrading cannot occur immediately, do not rely on verify-usb v2 results for removable drives that may have been physically accessed by an untrusted party.