# CVE-2026-3408: Open Babel CDXML File atom.cpp GetExplicitValence null pointer dereference

> A remote attacker can cause a denial of service via null pointer dereference in Open Babel's CDXML file handler.

- **Severity:** Medium 5.3 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 2 Mar 2026
- **Updated:** 2 Mar 2026
- **Also known as:** DEBIAN-CVE-2026-3408, GHSA-rxpr-wq63-jr7p, PYSEC-2026-2791, UBUNTU-CVE-2026-3408

## What is CVE-2026-3408?

CVE-2026-3408 is a medium-severity vulnerability in Open Babel, published on 2 Mar 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

A vulnerability was identified in Open Babel up to 3.1.1. This impacts the function OBAtom::GetExplicitValence of the file isrc/atom.cpp of the component CDXML File Handler. Such manipulation leads to null pointer dereference. The attack can be launched remotely. The exploit is publicly available and might be used. The name of the patch is e23a224b8fd9d7c2a7cde9ef4ec6afb4c05aa08a. It is best practice to apply a patch to resolve this issue.

Weakness: CWE-787 (Out-of-bounds Write), CWE-476 (NULL Pointer Dereference), CWE-404 (Improper Resource Shutdown or Release)

## Which versions are affected by CVE-2026-3408?

3 open source packages ship an affected version, including openbabel. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `openbabel` | PyPI | All versions | 3.2.0 |
| `openbabel` | PyPI | All versions | 3.2.0 |
| `openbabel` | PyPI | All versions | 3.2.0 |

Products: Openbabel Open Babel.

## How do I fix CVE-2026-3408?

Upgrade openbabel to 3.2.0 or later.

## Is CVE-2026-3408 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-3408 exists.

## Other vulnerabilities in Open Babel

- [CVE-2022-41793](https://insights.sbomify.com/CVE-2022-41793/): Open Babel has out-of-bounds write in CSR PadString (title field) (critical 9.8)
- [CVE-2022-42885](https://insights.sbomify.com/CVE-2022-42885/): Open Babel has uninitialized pointer dereference in GRO residue parser (critical 9.8)
- [CVE-2022-43467](https://insights.sbomify.com/CVE-2022-43467/): Open Babel has out-of-bounds write in PQS coord_file parser (critical 9.8)
- [CVE-2022-44451](https://insights.sbomify.com/CVE-2022-44451/): Open Babel has uninitialized pointer dereference in MSI atom parser (critical 9.8)
- [CVE-2022-46280](https://insights.sbomify.com/CVE-2022-46280/): Open Babel has uninitialized pointer dereference in PQS pFormat (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-3408 and fix it if it is affected.

What it is: CVE-2026-3408 is a medium-severity vulnerability in Open Babel, published on 2 Mar 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-3408 exists.

Affected packages and fixed versions:
- openbabel (PyPI): affected all versions; fixed in 3.2.0
- openbabel (PyPI): affected all versions; fixed in 3.2.0
- openbabel (PyPI): affected all versions; fixed in 3.2.0

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-2026-3408/ (Markdown: https://insights.sbomify.com/CVE-2026-3408/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-3408
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-3408
- OSV: https://osv.dev/vulnerability/CVE-2026-3408

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-3408/
Summaries are generated and may contain mistakes; the official description above is the record.