CVE-2026-19795: Qiskit SDK is vulnerable when deserializing QPY Files and may overflow the available stack space.
IBM Qiskit SDK 2.1.0 through 2.5.1 could allow a local attacker to cause a denial of service due to improper handling of a specially crafted object during deserialization. A malicious QPY payload can trigger a segmentation fault, causing the application to crash when deserializing untrusted input.
Other sources
Qiskit could allow a local attacker to cause a denial of service due to improper handling of a specially crafted object during deserialization. A malicious QPY payload can trigger a segmentation fault, causing the application to crash when deserializing untrusted input.
— IBM
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
Qiskit SDK (qiskit.qpy.load)to a version that resolves this vulnerability.Fixed in 2.5.2 - Compensating control
Avoid deserializing untrusted QPY files with qiskit.qpy.load() (only process QPY from trusted sources) to prevent a local attacker from triggering a crash/DoS via a specially crafted object.
Event History
Frequently Asked Questions
Who is exposed to this issue?
Applications using IBM Qiskit SDK versions 2.1.0 through 2.5.1 are exposed if they deserialize QPY files from untrusted sources.
What does an attacker need to exploit it?
An attacker needs the ability to provide a specially crafted QPY payload that the affected application will deserialize. The described attack is local and does not require privileges or user interaction.
What is the impact of successful exploitation?
Deserializing the malicious QPY payload can trigger a segmentation fault and crash the application, resulting in denial of service. No confidentiality or integrity impact is described.