# CVE-2026-4870: Denial of service in Qiskit SDK

> An attacker can cause a segmentation fault and denial of service in the Qiskit SDK by triggering uncontrolled recursion in the parser.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 12 Jun 2026
- **Updated:** 15 Jun 2026

## What is CVE-2026-4870?

CVE-2026-4870 is a high-severity denial of service vulnerability in IBM Qiskit SDK, published on 12 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official 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.

Weakness: CWE-674 (Uncontrolled Recursion)

## Which versions are affected by CVE-2026-4870?

It affects 1 product.


Products: Ibm Qiskit Software Development Kit.

## How do I fix CVE-2026-4870?

No fix has been published for CVE-2026-4870 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-4870 being exploited?

There is no known exploitation of CVE-2026-4870 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-4870 and fix it if it is affected.

What it is: CVE-2026-4870 is a high-severity denial of service vulnerability in IBM Qiskit SDK, published on 12 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-4870 in the wild and no public exploit code.

Affected product: IBM Qiskit SDK. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-4870/ (Markdown: https://insights.sbomify.com/CVE-2026-4870/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-4870
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-4870
- OSV: https://osv.dev/vulnerability/CVE-2026-4870

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-4870/
Summaries are generated and may contain mistakes; the official description above is the record.