CVE-2026-6844: binutils readelf DoS Vulnerability

CVE-2026-6844 Overview

A flaw was found in the readelf utility of the binutils package. A local attacker could exploit two Denial of Service (DoS) vulnerabilities by providing a specially crafted Executable and Linkable Format (ELF) file. One vulnerability, a resource exhaustion (CWE-400), can lead to an out-of-memory condition. The other, a null pointer dereference (CWE-476), can cause a segmentation fault. Both issues can result in the readelf utility becoming unresponsive or crashing, leading to a denial of service.

Critical Impact

Attackers can crash the readelf utility or exhaust system memory by providing maliciously crafted ELF files, disrupting binary analysis workflows and potentially affecting automated build pipelines.

Affected Products

• binutils package (readelf utility)

Discovery Timeline

• April 22, 2026 - CVE-2026-6844 published to NVD
• April 22, 2026 - Last updated in NVD database

Technical Details for CVE-2026-6844

Vulnerability Analysis

This vulnerability affects the readelf utility, a command-line tool within the binutils package used for displaying information about ELF (Executable and Linkable Format) files. The flaw consists of two distinct denial of service conditions that can be triggered through specially crafted ELF files.

The first issue involves resource exhaustion where the parsing logic fails to properly validate or limit resource consumption when processing malformed ELF structures. This can lead to excessive memory allocation, eventually exhausting available system memory and causing the utility to become unresponsive.

The second issue is a null pointer dereference that occurs when the utility encounters unexpected or missing data structures within the ELF file. When the code attempts to access memory through an uninitialized or null pointer, it triggers a segmentation fault, immediately terminating the process.

Both vulnerabilities require local access and user interaction—the target must be induced to analyze a malicious ELF file using the readelf command. While the impact is limited to availability (no confidentiality or integrity breach), these flaws could disrupt development workflows, automated security scanning, or build systems that rely on readelf for binary analysis.

Root Cause

The root cause stems from insufficient input validation when parsing ELF file structures. The resource exhaustion issue (CWE-400) results from the parser failing to enforce appropriate limits on memory allocation during ELF section or header processing. The null pointer dereference (CWE-476) occurs due to missing null checks before accessing parsed ELF data structures, allowing malformed files to trigger crashes when expected data elements are absent or invalid.

Attack Vector

The attack requires a local attacker to craft a malicious ELF file with specific structural anomalies designed to trigger either the memory exhaustion or null pointer dereference condition. The attacker must then convince a user or automated system to analyze this file using the readelf utility. Attack scenarios include:

• Submitting malicious binaries to automated CI/CD pipelines that perform binary analysis
• Sending crafted ELF files to security researchers or developers who analyze suspicious binaries
• Including malicious ELF files in software packages or archives that trigger readelf during extraction or verification

The vulnerability mechanism involves malformed ELF headers or sections that cause the parser to either allocate unbounded memory or dereference null pointers when expected structures are missing. For technical details on the specific ELF parsing flaws, refer to the Red Hat Bug Report #2460016.

Detection Methods for CVE-2026-6844

Indicators of Compromise

• Unexpected readelf process crashes (segmentation faults) in system logs
• Out-of-memory errors or excessive memory consumption by readelf processes
• Presence of unusually structured or malformed ELF files in analyzed directories
• Repeated readelf invocations followed by abnormal termination signals

Detection Strategies

• Monitor for SIGSEGV signals from readelf processes in system audit logs
• Implement memory usage thresholds for binary analysis tools to detect resource exhaustion attempts
• Use file integrity monitoring to identify potentially malicious ELF files before analysis
• Deploy sandbox environments for analyzing untrusted binary files

Monitoring Recommendations

• Configure process monitoring to alert on readelf crashes or abnormal terminations
• Set up resource usage alerts for memory consumption spikes during binary analysis operations
• Implement logging for all readelf invocations with file hash correlation for forensic analysis
• Monitor CI/CD pipeline logs for binary analysis tool failures that could indicate exploitation attempts

How to Mitigate CVE-2026-6844

Immediate Actions Required

• Avoid analyzing untrusted ELF files with readelf until patches are applied
• Run readelf operations in sandboxed or containerized environments with resource limits
• Update binutils package to the latest patched version when available from your distribution
• Implement memory and CPU limits for binary analysis processes using cgroups or similar controls

Patch Information

No vendor patches have been confirmed at this time. Monitor the Red Hat CVE-2026-6844 Advisory for patch availability and distribution-specific updates. Subscribe to your Linux distribution's security mailing list for binutils security updates.

Workarounds

• Execute readelf within containers or VMs with strict resource limits to contain potential denial of service impacts
• Implement input validation for ELF files before processing using alternative tools with better error handling
• Use ulimit to restrict memory allocation for readelf processes: ulimit -v 524288 (512MB limit)
• Consider alternative ELF analysis tools such as objdump or llvm-readelf which may not share the same vulnerabilities

# Configuration example - Resource limits for readelf operations
# Set memory limit for readelf process
ulimit -v 524288  # 512MB virtual memory limit

# Run readelf in a restricted container
docker run --rm --memory=512m --memory-swap=512m \
  --read-only -v /path/to/file:/elf:ro \
  binutils-container readelf -a /elf/suspicious.elf

# Use systemd resource controls for automated analysis
systemd-run --scope -p MemoryMax=512M readelf -a suspicious.elf