CVE-2026-4870
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedIBM 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.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceIBM Qiskit SDK versions 0.43.0 through 2.5.0 contains an uncontrolled recursion vulnerability in its parser. By supplying specially crafted input to the parser, an attacker can cause excessive recursive calls that lead to a segmentation fault, resulting in denial of service.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data>= 0.43.0, < 1.4.6>= 2.0.0, < 2.4.2CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
-
Identify installed Qiskit SDK versionRun 'pip show qiskit' or 'python -c "import qiskit; print(qiskit.__version__)"' to retrieve the installed version numberAffected if The version displayed is >= 0.43.0 and < 1.4.6, or >= 2.0.0 and < 2.4.2
-
Verify Qiskit parser is in useCheck if your code or workflows invoke Qiskit parsing functions such as qiskit.circuit.assemble, qiskit.qasm.Qasm, or circuit.from_qasm_str() which utilize the internal parserAffected if Parser functions are called with untrusted or user-supplied QASM or circuit definition input
-
Inspect for crash logs or segmentation faultsReview application logs, system logs (dmesg), or crash reports for segmentation faults occurring during Qiskit parsing operationsAffected if Segmentation faults are logged in proximity to Qiskit parser invocations with no other identifiable cause
-
Check Python recursion depth configurationRun 'python -c "import sys; print(sys.getrecursionlimit())"' to see current recursion limit; default is typically 1000Affected if The recursion limit is set very high (above default) which could exacerbate the uncontrolled recursion condition
Your environment is affected if Qiskit SDK version falls within 0.43.0 to 1.4.5 or 2.0.0 to 2.4.1 AND the parser processes external or untrusted input.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scoped1.4.62.4.2
Upgrade to a patched version of IBM Qiskit SDK beyond 2.5.0 once available, or implement input validation/recursion limits in the parser to prevent stack overflow.
Upgrade to Qiskit 1.4.6 (for 0.x/1.x users) or 2.4.2 (for 2.x users)
- Check current installed Qiskit version using: pip show qiskit or python -c "import qiskit; print(qiskit.__version__)"
- Determine which major version branch you are on (0.x/1.x or 2.x)
- If using Qiskit 0.x or 1.x: upgrade to version 1.4.6 or later using: pip install --upgrade qiskit>=1.4.6
- If using Qiskit 2.x: upgrade to version 2.4.2 or later using: pip install --upgrade qiskit>=2.4.2
- Verify the upgrade was successful by checking the installed version
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation3.0 h
- Implementation8.0 h
- Testing4.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $4,800.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-4870 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-4870 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.
A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.
- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
- No spam, self-promotion, credentials, or personal data