CVE-2026-2705: Open Babel RCE Vulnerability

CVE-2026-2705 Overview

A memory safety vulnerability has been identified in Open Babel, an open-source chemistry toolbox used for converting chemical file formats, searching, fingerprinting, and performing molecular mechanics. The vulnerability exists in the OBAtom::SetFormalCharge function within the include/openbabel/atom.h library header file, specifically when processing MOL2 files. This out-of-bounds read condition can be triggered remotely through maliciously crafted MOL2 files.

Critical Impact

Remote attackers can exploit this out-of-bounds read vulnerability by supplying specially crafted MOL2 files, potentially leading to information disclosure or application crashes. A proof-of-concept exploit is publicly available, increasing the risk of exploitation.

Affected Products

• Open Babel up to version 3.1.1
• Applications utilizing the Open Babel MOL2 file parsing library
• Software incorporating include/openbabel/atom.h component

Discovery Timeline

• 2026-02-19 - CVE-2026-2705 published to NVD
• 2026-02-19 - Last updated in NVD database

Technical Details for CVE-2026-2705

Vulnerability Analysis

This vulnerability is classified as an out-of-bounds read (CWE-119: Improper Restriction of Operations within the Bounds of a Memory Buffer). The flaw resides in the MOL2 file handler component of Open Babel, specifically within the OBAtom::SetFormalCharge function. When processing malformed MOL2 molecular structure files, the function fails to properly validate input boundaries before accessing memory, allowing read operations beyond the allocated buffer limits.

The attack can be conducted remotely since MOL2 files can be transmitted over the network and processed by vulnerable installations. While the primary impact is limited to availability (causing application instability or crashes), out-of-bounds read vulnerabilities can potentially expose sensitive memory contents depending on the application context.

Root Cause

The root cause lies in insufficient bounds checking within the OBAtom::SetFormalCharge function when parsing MOL2 file data. The function does not adequately validate that input data falls within expected memory boundaries before processing formal charge assignments for molecular atoms. This allows crafted MOL2 files to trigger memory reads outside the intended buffer space.

Attack Vector

The vulnerability is exploitable via network-based attacks where an attacker supplies a maliciously crafted MOL2 file to a system running vulnerable Open Babel software. The attack requires user interaction, such as opening or processing the malicious file. The exploit has been made publicly available, and a proof-of-concept MOL2 file demonstrating the vulnerability can be found in the GitHub PoC repository.

The vulnerability manifests when the MOL2 file handler processes specially crafted molecular structure data that triggers the out-of-bounds read condition in the OBAtom::SetFormalCharge function. For technical details on the specific crafted file format that triggers this condition, refer to the GitHub issue discussion where the vulnerability was reported.

Detection Methods for CVE-2026-2705

Indicators of Compromise

• Unexpected crashes or segmentation faults in applications using Open Babel when processing MOL2 files
• Application log entries showing memory access violations in the atom.h component
• Processing of MOL2 files from untrusted or unexpected sources
• Abnormal memory consumption patterns during chemical file conversions

Detection Strategies

• Monitor application logs for crashes or errors related to Open Babel MOL2 file processing
• Implement file integrity monitoring for MOL2 files entering the system
• Deploy endpoint detection solutions capable of identifying memory corruption exploit attempts
• Review application crash dumps for evidence of out-of-bounds memory access patterns

Monitoring Recommendations

• Enable verbose logging for Open Babel-dependent applications to capture file processing events
• Configure memory protection mechanisms like ASLR and DEP to mitigate exploitation impact
• Monitor for unusual MOL2 file transfers from external sources
• Implement network-based detection for potentially malicious molecular structure files

How to Mitigate CVE-2026-2705

Immediate Actions Required

• Restrict processing of MOL2 files from untrusted sources until patches are available
• Implement input validation for all molecular structure files before Open Babel processing
• Consider sandboxing Open Babel operations to limit potential impact
• Monitor the official Open Babel GitHub repository for vendor response and patch availability

Patch Information

As of the last update, the Open Babel project maintainers have been notified of this vulnerability through a GitHub issue report but have not yet responded. No official patch is currently available. Users should monitor the Open Babel GitHub repository and project communications for security updates. The vulnerability is tracked at VulDB for additional details.

Workarounds

• Validate and sanitize all MOL2 files before processing through Open Babel
• Implement file type verification to ensure only legitimate MOL2 files are processed
• Run Open Babel in a sandboxed or containerized environment to limit impact of exploitation
• Consider using alternative molecular file formats where possible until a patch is released

In the absence of an official patch, organizations can implement additional security controls by validating MOL2 file structure before processing. Ensure that any file handling operations include proper error handling to gracefully manage malformed input.