CVE-2026-6845: binutils readelf Utility DoS Vulnerability

CVE-2026-6845 Overview

A flaw was found in binutils, specifically within the readelf utility. This vulnerability allows a local attacker to cause a Denial of Service (DoS) by tricking a user into processing a specially crafted Executable and Linkable Format (ELF) file. The exploitation of this flaw can lead to the system becoming unresponsive due to excessive resource consumption or a program crash.

Critical Impact

Local attackers can exploit this Null Pointer Dereference vulnerability (CWE-476) to crash the readelf utility or cause system unresponsiveness when users process maliciously crafted ELF files.

Affected Products

• GNU binutils (versions containing the vulnerable readelf utility)
• Linux distributions shipping affected binutils packages

Discovery Timeline

• 2026-04-22 - CVE CVE-2026-6845 published to NVD
• 2026-04-22 - Last updated in NVD database

Technical Details for CVE-2026-6845

Vulnerability Analysis

This vulnerability is classified as a Null Pointer Dereference (CWE-476) affecting the readelf utility within the GNU binutils package. The flaw occurs when readelf processes specially crafted ELF files that trigger a code path where a null pointer is dereferenced, leading to a crash or denial of service condition.

The attack requires local access and user interaction, meaning an attacker must convince a victim to open or analyze a malicious ELF file using readelf. This could occur in various scenarios such as security analysts examining suspicious binaries, developers working with third-party libraries, or automated build systems processing untrusted code.

The primary impact is availability-focused, as successful exploitation results in the readelf process terminating unexpectedly or consuming excessive resources. While the vulnerability does not directly lead to data confidentiality or integrity breaches, it can disrupt development workflows and security analysis operations.

Root Cause

The root cause is a Null Pointer Dereference (CWE-476) within the readelf utility's ELF file parsing logic. When encountering specific malformed structures in an ELF file, the code fails to properly validate pointer values before dereferencing them, leading to an unhandled null pointer access that crashes the application.

Attack Vector

The attack vector is local, requiring an attacker to deliver a specially crafted ELF file to a victim and convince them to analyze it using the readelf utility. This could be achieved through:

• Distributing malicious ELF binaries via email, downloads, or file sharing
• Embedding malicious ELF files in software packages or repositories
• Targeting automated build or analysis systems that process untrusted ELF files

The vulnerability requires user interaction to exploit, as the victim must explicitly run readelf against the malicious file.

Detection Methods for CVE-2026-6845

Indicators of Compromise

• Unexpected crashes of readelf processes when analyzing ELF files
• Core dumps generated from readelf with null pointer dereference signatures
• Repeated readelf process terminations in system logs

Detection Strategies

• Monitor for abnormal termination of readelf processes, particularly segmentation faults
• Implement file integrity monitoring for ELF files in critical directories
• Configure crash reporting to capture and analyze readelf crashes for potential exploitation attempts

Monitoring Recommendations

• Enable process monitoring for binutils utilities including readelf
• Configure logging to capture command-line arguments passed to readelf invocations
• Implement sandbox or container isolation for ELF file analysis workflows

How to Mitigate CVE-2026-6845

Immediate Actions Required

• Avoid processing ELF files from untrusted sources with readelf until patches are applied
• Implement sandbox isolation when analyzing potentially malicious ELF files
• Update binutils packages when vendor patches become available

Patch Information

Refer to the Red Hat CVE-2026-6845 Advisory for official patch information and affected package versions. Additional technical details can be found in the Red Hat Bug Report #2460012.

Organizations should monitor their Linux distribution's security advisories for patched binutils packages.

Workarounds

• Use alternative ELF analysis tools such as objdump with appropriate caution until readelf is patched
• Analyze untrusted ELF files within isolated virtual machines or containers
• Implement strict input validation and file type verification before processing ELF files
• Restrict user permissions to limit impact of potential DoS conditions

# Example: Run readelf in an isolated container for untrusted files
podman run --rm -v /path/to/suspicious/file:/data:ro fedora:latest readelf -a /data/suspicious.elf