# CVE-2026-47143: Capstone has a NULL Pointer Dereference with 3DNow! opcodes

> A remote attacker can crash applications using the reduced X86 Capstone library by supplying crafted 3DNow! opcodes, causing a denial of service.

- **Severity:** Medium 5.1 (`CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 21 Jul 2026
- **Updated:** 22 Jul 2026
- **Also known as:** AZL-92879, AZL-93312, BELL-CVE-2026-47143, DEBIAN-CVE-2026-47143, GHSA-289w-cm54-fgrm, PYSEC-2026-3544, RHSA-2026:43841, UBUNTU-CVE-2026-47143

## What is CVE-2026-47143?

CVE-2026-47143 is a medium-severity vulnerability in capstone-engine capstone, published on 21 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

Capstone is a disassembly framework. Versions prior to 6.0.0-Alpha8 and 5.0.8 have a NULL pointer dereference in `modRMRequired()` and `decode()` when disassembling 3DNow! opcodes (`0F 0F`) in builds compiled with `-DCAPSTONE_X86_REDUCE`, allowing a remote attacker to crash any application using the reduced X86 Capstone library by supplying a crafted input containing the 4-byte sequence `0F 0F <modrm> <imm8>`. Versions 6.0.0-Alpha8 and 5.0.8 patch the issue.

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2026-47143?

1 open source package ship an affected version, including capstone. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `capstone` | PyPI | All versions | 5.0.8 |
| `capstone` | Red Hat:hummingbird:1 | All versions | 0:5.0.8-0.1.hum1 |
| `capstone-devel` | Red Hat:hummingbird:1 | All versions | 0:5.0.8-0.1.hum1 |
| `capstone-java` | Red Hat:hummingbird:1 | All versions | 0:5.0.8-0.1.hum1 |
| `capstone-static` | Red Hat:hummingbird:1 | All versions | 0:5.0.8-0.1.hum1 |
| `python3-capstone` | Red Hat:hummingbird:1 | All versions | 0:5.0.8-0.1.hum1 |

Products: Capstone-Engine Capstone.

## How do I fix CVE-2026-47143?

Upgrade capstone to 5.0.8 or later.

## Is CVE-2026-47143 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-47143 exists.

## Other vulnerabilities in capstone-engine capstone

- [CVE-2017-6952](https://insights.sbomify.com/CVE-2017-6952/): Capstone Integer overflow (high 8.8)
- [CVE-2016-7151](https://insights.sbomify.com/CVE-2016-7151/): Capstone SEGV caused by a read memory access (medium 5.5)
- [CVE-2025-67873](https://insights.sbomify.com/CVE-2025-67873/): Capstone doesn't check Skipdata length, leading to cs_insn.bytes heap buffer overflow (medium 4.8)
- [CVE-2025-68114](https://insights.sbomify.com/CVE-2025-68114/): Capstone doesn't check vsnprintf return in SStream_concat, allows stack buffer underflow and overflow (medium 4.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-47143 and fix it if it is affected.

What it is: CVE-2026-47143 is a medium-severity vulnerability in capstone-engine capstone, published on 21 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-47143 exists.

Affected packages and fixed versions:
- capstone (PyPI): affected all versions; fixed in 5.0.8

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-2026-47143/ (Markdown: https://insights.sbomify.com/CVE-2026-47143/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-47143
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-47143
- OSV: https://osv.dev/vulnerability/CVE-2026-47143

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-47143/
Summaries are generated and may contain mistakes; the official description above is the record.