CVE-2026-4647: GNU Binutils BFD Library DoS Vulnerability

CVE-2026-4647 Overview

A flaw was found in the GNU Binutils BFD library, a widely used component for handling binary files such as object files and executables. The issue occurs when processing specially crafted XCOFF object files, where a relocation type value is not properly validated before being used. This can cause the program to read memory outside of intended bounds. As a result, affected tools may crash or expose unintended memory contents, leading to denial-of-service or limited information disclosure risks.

Critical Impact

This out-of-bounds read vulnerability (CWE-125) in the GNU Binutils BFD library can cause application crashes and potential information disclosure when processing malicious XCOFF object files, affecting development tools and build systems across multiple platforms.

Affected Products

• GNU Binutils (all versions)
• Red Hat OpenShift Container Platform 4.0
• Red Hat Enterprise Linux 6.0, 7.0, 8.0, 9.0, 10.0

Discovery Timeline

• 2026-03-23 - CVE-2026-4647 published to NVD
• 2026-03-24 - Last updated in NVD database

Technical Details for CVE-2026-4647

Vulnerability Analysis

The vulnerability exists in the Binary File Descriptor (BFD) library, which is a core component of GNU Binutils used by tools such as objdump, readelf, nm, and the GNU linker (ld). The BFD library provides a common interface for reading and writing object files in various formats.

When the library processes XCOFF (Extended Common Object File Format) object files—a format primarily used on IBM AIX systems—it fails to properly validate relocation type values before using them as array indices or in other memory-related operations. This improper input validation allows an attacker to craft a malicious XCOFF file that triggers an out-of-bounds memory read.

The vulnerability requires local access and user interaction, as a user must open or process the malicious file using a Binutils tool. While this limits the attack surface, build systems and automated toolchains that process untrusted input files could be particularly vulnerable.

Root Cause

The root cause is an improper input validation issue (CWE-125 - Out-of-Bounds Read) in the XCOFF file parsing code within the BFD library. Specifically, the relocation type field from the XCOFF file is used without first verifying that it falls within the expected range of valid values. When an attacker provides an out-of-range value, the code may attempt to access memory beyond the intended buffer boundaries.

Attack Vector

The attack vector is local, requiring an attacker to either:

1. Convince a user to open or process a malicious XCOFF object file using tools like objdump, readelf, or nm
2. Plant a malicious XCOFF file in a location where it will be processed by automated build systems or CI/CD pipelines
3. Submit a malicious object file to a service that uses Binutils for binary analysis

The vulnerability manifests when the BFD library parses the relocation section of a specially crafted XCOFF file. The relocation type value is not bounds-checked before being used, allowing memory contents outside the intended buffer to be read. This can result in application crashes due to accessing invalid memory regions, or potentially expose sensitive information from process memory.

For technical details on the vulnerability, see Sourceware Bugzilla #33919.

Detection Methods for CVE-2026-4647

Indicators of Compromise

• Unexpected crashes in Binutils tools (objdump, readelf, nm, ld) when processing object files
• Core dumps from BFD library components showing out-of-bounds memory access
• Suspicious XCOFF format files appearing in build directories or repositories
• Unusual memory access patterns in processes using the BFD library

Detection Strategies

• Monitor for abnormal termination of Binutils processes with SIGSEGV or SIGBUS signals
• Implement file type validation to detect potentially malicious XCOFF files before processing
• Use AddressSanitizer (ASan) builds of Binutils in test environments to catch out-of-bounds reads
• Deploy endpoint detection to identify exploitation attempts targeting development tools

Monitoring Recommendations

• Enable crash monitoring and logging for all Binutils components in build environments
• Audit build pipelines for processing of untrusted or external object files
• Review system logs for repeated failures in binary analysis tools
• Implement file integrity monitoring for development toolchain executables

How to Mitigate CVE-2026-4647

Immediate Actions Required

• Avoid processing untrusted XCOFF object files until patches are applied
• Restrict access to Binutils tools in multi-user environments
• Isolate build processes that handle external or untrusted binary files using containers or sandboxing
• Review and update Binutils packages when security updates become available from your distribution

Patch Information

Security updates are expected from GNU Binutils upstream and downstream distributions. Organizations should monitor the following resources for patches:

• Red Hat CVE-2026-4647 Advisory - Official Red Hat security advisory with patch information
• Red Hat Bugzilla #2450302 - Red Hat bug tracker for this vulnerability
• Sourceware Bugzilla #33919 - Upstream GNU Binutils bug report

Apply vendor-provided patches as soon as they become available. For Red Hat Enterprise Linux and OpenShift Container Platform users, check the Red Hat Customer Portal for updated packages.

Workarounds

• Run Binutils tools in sandboxed environments (containers, VMs, or restricted namespaces) when processing untrusted files
• Implement input validation to reject XCOFF files from untrusted sources before processing
• Use file type detection to identify and quarantine suspicious object files before they reach build systems
• Consider using alternative binary analysis tools that do not rely on the vulnerable BFD library for XCOFF parsing

# Example: Sandbox Binutils with limited capabilities using firejail
firejail --noprofile --quiet --private-tmp objdump -d untrusted_file.o

# Example: Use file command to identify XCOFF files for additional scrutiny
file suspicious_file.o | grep -i "xcoff" && echo "XCOFF file detected - handle with caution"