# CVE-2026-116499: IBM Qiskit SDK unsafe deserialization in QPY format

Source: https://junglewise.ai/threats/cve-2026-116499-ibm-qiskit-sdk-1-4-2-through-2-6-2-could-allow-a-local-attacker  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-11-08. Updated: 2026-11-08  
License: CC BY 4.0 with a link back

CVE-2026-116499 · Severity: high · CVSS 8.4 · Published 2026-11-08

IBM Qiskit SDK is a quantum computing framework used by developers to build and simulate quantum algorithms. A flaw in how it processes QPY (Qiskit Pickle YAML) format files allows arbitrary Python code execution when loading a malicious file, potentially giving an attacker complete control over the developer's system. An attacker with local access or ability to deliver a crafted QPY file could run any code at the privilege level of the Python process.

Technologies: [IBM Qiskit SDK](https://junglewise.ai/threats/technologies/qiskit-sdk). Vendors: [IBM](https://junglewise.ai/threats/vendors/ibm).

## Quick answers

**Is CVE-2026-116499 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-116499 being exploited in the wild.

**How severe is CVE-2026-116499?** High severity, with a CVSS score of 8.4, published 8 November 2026.

**Which products and versions are affected?** IBM Qiskit SDK 1.4.2 through 2.6.1.

**Is there a fix for CVE-2026-116499?** Yes: fixed in Qiskit SDK v2.6.2. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-116499 attacked?** It is attacked with local access, in a software library.

**Am I affected by CVE-2026-116499?** Check whether you run IBM Qiskit SDK at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- Fixed in Qiskit SDK v2.6.2

## Technical details

The vulnerability exists in Qiskit's qiskit.qpy.load() function, which unsafely deserializes untrusted QPY format payloads (versions <13) by internally using SymPy without proper validation. An attacker can embed arbitrary Python code in a specially crafted QPY binary file; when deserialized, this code executes unconditionally. The attack requires local file access or user interaction to load the malicious file, but no privilege escalation or authentication is required. The fix in v2.6.2 removes SymPy from the deserialization path.

## Affected products

- IBM Qiskit SDK 1.4.2 through 2.6.1

## Timeline

- 2026-11-05: disclosed
- 2026-11-08: advisory

## References

- [https://www.ibm.com/support/pages/node/7295238](https://www.ibm.com/support/pages/node/7295238)

## Related threats

- [IBM Qiskit SDK out-of-bounds write in unitary matrix handler](https://junglewise.ai/threats/cve-2026-116501-ibm-qiskit-sdk-2-4-0-through-2-6-1-could-allow-a-local-attacker)
- [IBM Qiskit SDK unbound recursion in QPY deserialization](https://junglewise.ai/threats/cve-2026-116500-ibm-qiskit-sdk-2-4-0-through-2-6-1-could-allow-a-local-attacker)
- [Qiskit SDK stack overflow in QPY deserialization](https://junglewise.ai/threats/cve-2026-19795-qiskit-sdk-stack-overflow-in-qpy-deserialization)
- [IBM Qiskit SDK denial of service via uncontrolled recursion in parser](https://junglewise.ai/threats/cve-2026-4870-ibm-qiskit-sdk-denial-of-service-via-uncontrolled-recursion-in)