CVE-2026-4870Qiskit SDK is vulnerable to specific functions may recurse too deeply and overflow the available stack space, when encountering certain classical expressions.
- 7.5HighCVSS base score
- 0.27%Exploitation in 30 daysEPSS · top 81% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
Description
IBM Qiskit SDK 0.43.0 through 2.5.0 could allow an attacker to trigger a segmentation fault leading to a denial of service due to uncontrolled recursion in the parser.
Timeline
ID reserved
By ibm
- 3 months later
· 3 months later
Published
- 3 days later
· 3 days later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| ibmCNA (assigner) | 3.1 | High7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
| NVDNVD · Analyzed | 3.1 | High7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
- EPSS (exploitation in 30 days)
- 0.27% · top 81% of all CVEs (14 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: yes · Technical impact: partial
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.5.
Affected products
- affected 0.43.0 – ≤ 2.5.0
What to do
Solution: Remediation/Fixes guidance: The issue is addressed in Qiskit versions v1.4.6 and v2.4.2. These are patched to error with a Python-space RecursionError exception once the expression depth exceeds the Python recursion limit which can be queried with sys.getrecursionlimit(). This limit can be adjusted by calling sys.setrecursionlimit(). Future versions of Qiskit may remove this limit entirely with a non-recursive version of the OpenQASM 2 parser. Product(s)Version(s) number and/or range Remediation/Fix/Instructions<Qiskit SDK - qiskit.qasm2.loads() function>v1.4.6 and v2.4.2 Upgrade to the patched versions: qiskit v1.4.6 or qiskit v2.4.2. <Qiskit SDK - QuantumCircuit.from_qasm_str function>v1.4.6 and v2.4.2 Upgrade to the patched versions: qiskit v1.4.6 or qiskit v2.4.2. <Qiskit SDK - QuantumCircuit.from_qasm_str function>v1.4.6 and v2.4.2 Upgrade to the patched versions: qiskit v1.4.6 or qiskit v2.4.2.
Workaround: Workarounds/Mitigation guidance: None
References
References1
- https://www.ibm.com/support/pages/node/7276123 (opens in a new tab)vendor-advisorypatch
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2026-36575 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2026-4870)Record last updated .