Quick answers
- Is CVE-2026-4870 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-4870 being exploited in the wild.
- How severe is CVE-2026-4870?
- High severity, with a CVSS score of 7.5, published 12 June 2026.
- Which products and versions are affected?
- IBM Qiskit SDK 0.43.0 - 2.5.0.
- Is there a fix for CVE-2026-4870?
- A patch was published on 2026-06-12. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
- How is CVE-2026-4870 attacked?
- It is attacked over the network, in a software library.
- Am I affected by CVE-2026-4870?
- 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.
Technical details
A vulnerability in the OpenQASM 2 parser of the IBM Qiskit SDK (specifically within qiskit.qasm2.load, qiskit.qasm2.loads, and QuantumCircuit.from_qasm_str) allows for uncontrolled recursion. When the parser encounters deeply nested classical expressions, it can overflow the available stack space, resulting in a segmentation fault. This is a remote attack vector if the application processes user-supplied QASM strings or files without prior validation. The issue is mitigated in patched versions by enforcing the Python recursion limit and raising a standard RecursionError instead of crashing the process. Patches are available in versions 1.4.6 and 2.4.2.
Affected products
- IBM Qiskit SDK 0.43.0 - 2.5.0
Timeline
- 2026-06-12: disclosed
- 2026-06-12: advisory
- 2026-06-12: patched