CVE-2025-1403 is a high-severity vulnerability identified in the IBM Qiskit SDK versions 0.45.0 through 1.2.4. The vulnerability arises from improper deserialization of untrusted data, specifically within the handling of QPY files that contain a malformed symengine serialization stream. QPY files are used by Qiskit to serialize quantum circuits and related data. The malformed serialization stream can trigger a segmentation fault (segfault) in the symengine library, which is a symbolic manipulation library used by Qiskit. This segfault leads to a denial of service (DoS) condition, causing the affected application or service to crash or become unresponsive. The vulnerability does not require any authentication or user interaction and can be exploited remotely by an attacker who can supply a malicious QPY file to the target system. The CVSS v3.1 base score is 8.6, reflecting the high impact on availability with no impact on confidentiality or integrity. The scope is changed (S:C), indicating that the vulnerability affects components beyond the initially vulnerable component, potentially impacting the entire system or environment running Qiskit. No known exploits are currently reported in the wild, and no patches or fixes have been linked yet. The root cause is classified under CWE-502 (Deserialization of Untrusted Data), a common issue where untrusted input is deserialized without proper validation or sanitization, leading to memory corruption or crashes. This vulnerability is particularly relevant for environments that process quantum computing workloads using Qiskit SDK, especially where QPY files are accepted from external or untrusted sources.

For European organizations, the impact of CVE-2025-1403 primarily concerns availability disruption of quantum computing workflows that rely on the IBM Qiskit SDK. Organizations involved in quantum research, development, or those integrating quantum computing into their operations could experience service outages or crashes if malicious QPY files are processed. This could delay critical computations, research projects, or business processes dependent on quantum simulations or quantum circuit executions. While the vulnerability does not compromise confidentiality or integrity, the denial of service could affect operational continuity and productivity. Given the emerging nature of quantum computing, affected organizations may include academic institutions, research labs, technology companies, and government agencies engaged in quantum initiatives. The lack of authentication or user interaction requirements means that any system accepting QPY files from external sources is at risk, increasing the attack surface. Additionally, the changed scope of the vulnerability suggests that the impact could extend beyond the Qiskit SDK to other components or services relying on it, potentially amplifying the disruption. The absence of known exploits in the wild provides a window for proactive mitigation, but the high CVSS score indicates that exploitation would be straightforward and impactful once an exploit is developed.

To mitigate CVE-2025-1403, European organizations should implement the following specific measures: 1) Restrict and validate input sources: Only accept QPY files from trusted and authenticated sources. Implement strict input validation and integrity checks on QPY files before processing. 2) Isolate Qiskit processing environments: Run Qiskit workloads in sandboxed or containerized environments to limit the impact of potential crashes and prevent cascading failures. 3) Monitor and log QPY file handling: Deploy monitoring solutions to detect abnormal crashes or segfaults related to Qiskit processes and investigate suspicious QPY file submissions. 4) Apply principle of least privilege: Ensure that processes handling QPY files run with minimal privileges to reduce the potential damage from a DoS event. 5) Stay updated on vendor patches: Regularly check IBM security advisories for patches or updates addressing this vulnerability and apply them promptly once available. 6) Develop incident response plans: Prepare for potential DoS incidents by having recovery procedures to quickly restart affected services and restore operational continuity. 7) Educate developers and users: Raise awareness about the risks of deserializing untrusted data and encourage secure coding practices when handling QPY files or similar serialized data formats. These targeted actions go beyond generic advice by focusing on controlling input sources, environment isolation, and proactive monitoring specific to the Qiskit SDK context.