CVE-2026-116501 PUBLISHED

Qiskit SDK C API may trigger an out of bounds write on accessing the unitary matrix with qk_circuit_inst_unitary().

Assigner: ibm
Reserved: 26.10.2026 Published: 08.11.2026 Updated: 09.11.2026

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.

Metrics

CVSS 3.1

CVSS Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CVSS Score: 8.4

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

CVSS 3.1

Product Status

Vendor	IBM
Product	Qiskit SDK
Versions	affected from 2.4.0 to 2.6.1 (incl.)

Workarounds

Workarounds/Mitigation guidance:

None

Solutions

Remediation/Fixes guidance:

The issue is addressed in Qiskit versions v2.6.2. This version is patched to detect this situation and write out a sentinel value to identify the instruction is in an inconsistent state.

Product(s)Version(s) number and/or range Remediation/Fix/Instructions< Qiskit SDK https://github.com/qiskit/qiskit - qk_circuit_inst_unitary() function>v2.6.2

Upgrade to the patched versions: qiskit v2.6.2.

Credits

The vulnerability was reported to IBM by Nathan Rebello. finder

References

https://www.ibm.com/support/pages/node/7295237

Problem Types

CWE-787 Out-of-bounds Write CWE