# CVE-2026-116500: IBM Qiskit SDK unbound recursion in QPY deserialization

Source: https://junglewise.ai/threats/cve-2026-116500-ibm-qiskit-sdk-2-4-0-through-2-6-1-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-2026-116500 · Severity: medium · CVSS 6.2 · Published 2026-11-08

IBM Qiskit SDK is a quantum computing framework used to develop and simulate quantum programs. Versions 2.4.0 through 2.6.1 are vulnerable to a denial-of-service attack when processing maliciously crafted quantum program files, allowing a local attacker to crash the application and disrupt quantum computing tasks. The vulnerability stems from uncontrolled recursion during file parsing that can exhaust available memory.

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

## Quick answers

**Is CVE-2026-116500 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-116500 being exploited in the wild.

**How severe is CVE-2026-116500?** Medium severity, with a CVSS score of 6.2, published 8 November 2026.

**Which products and versions are affected?** IBM Qiskit SDK 2.4.0 through 2.6.1.

**Is there a fix for CVE-2026-116500?** 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-2026-116500 attacked?** It is attacked with local access, in a software library.

**Am I affected by CVE-2026-116500?** 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

Unbound recursion in QPY format deserialization (qiskit.qpy.load() function) for format versions ≥13 allows processing of maliciously crafted payloads to exceed stack limits and trigger segmentation faults. The vulnerability affects deserialization of untrusted QPY data with no authentication or special permissions required; local attacker access is necessary. A fix is available in version 2.6.2.

## Affected products

- IBM Qiskit SDK 2.4.0 through 2.6.1

## Timeline

- 2026-11-05: disclosed

## References

- [https://www.ibm.com/support/pages/node/7295235](https://www.ibm.com/support/pages/node/7295235)

## 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 unsafe deserialization in QPY format](https://junglewise.ai/threats/cve-2026-116499-ibm-qiskit-sdk-1-4-2-through-2-6-2-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)