QISKIT · CVE-2026-116501 · Package
FIX → 2.6.2 ✓ verified
Qiskit 2.4.0 through 2.6.1: the C API function qk_circuit_inst_unitary() can write more data than documented if a logic fault leaves a circuit in an allowed but inconsistent state. Maintainers say this could potentially be triggered by loading a corrupted or maliciously constructed QPY file. Fixed in 2.6.2.
first public Nov 8, 2026 · 2 sources
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Qiskit (pip) 2.4.0 through 2.6.1. The advisory names the C API function qk_circuit_inst_unitary(); it says the bug could potentially be triggered by loading a corrupted or maliciously constructed QPY file. Teams that use Qiskit only from Python without the C API, or only load QPY files they produced themselves, can likely skip it, though the advisory does not state this explicitly.
Not affected if no-c-api-use, trusted-qpy-only, version-2.6.2-or-later, version-outside-2.4.0-to-2.6.1
Who cares c-api, python, qiskit, qpy, quantum
pip show qiskit; versions >= 2.4.0 and <= 2.6.1 are affected, 2.6.2 is patched.IBM Qiskit SDK 2.4.0 through 2.6.1 could allow a local attacker to execute arbitrary code due to an out-of-bounds write caused by improper input validation when accessing a corrupted unitary matrix.
This page as .md · .json · CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
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Upgrade to 2.6.2
Upgrade qiskit to 2.6.2 (pip install -U qiskit>=2.6.2)