CVE-2025-69649: GNU Binutils Denial of Service Vulnerability

CVE-2025-69649 Overview

GNU Binutils through version 2.46 contains a null pointer dereference vulnerability in the readelf utility. The flaw occurs when processing a crafted ELF binary with malformed header fields. During relocation processing, an invalid or null section pointer may be passed into the display_relocations() function, resulting in a segmentation fault (SIGSEGV) and abrupt termination of the application. This denial of service vulnerability can be triggered remotely by convincing a user to analyze a malicious ELF file.

Critical Impact

Attackers can crash the readelf utility by supplying specially crafted ELF binaries, causing denial of service for security researchers, reverse engineers, and automated analysis pipelines that depend on GNU Binutils.

Affected Products

• GNU Binutils through version 2.46

Discovery Timeline

• 2026-03-06 - CVE-2025-69649 published to NVD
• 2026-03-11 - Last updated in NVD database

Technical Details for CVE-2025-69649

Vulnerability Analysis

This vulnerability is classified as CWE-476 (NULL Pointer Dereference). The core issue lies in insufficient validation of section pointers during ELF relocation processing within the readelf utility. When readelf encounters an ELF binary with malformed or corrupted header fields, the relocation processing code path fails to properly validate that section pointers are non-null before dereferencing them.

The vulnerability specifically manifests in the display_relocations() function, which attempts to access section data without adequate null pointer checks. When a null section pointer is passed to this function, the application attempts to dereference invalid memory, triggering a SIGSEGV signal and immediate process termination.

Importantly, security analysis indicates no evidence of memory corruption beyond the null pointer dereference itself. The crash is deterministic and does not appear to provide any pathway for code execution or data exfiltration.

Root Cause

The root cause is improper input validation in the ELF parsing code. The readelf utility trusts certain header field values without adequately verifying that referenced sections actually exist and are properly initialized. When processing relocations, the code assumes section pointers are valid, but malformed ELF files can violate this assumption by specifying invalid section indices or corrupted header values that result in null section pointers being passed to display functions.

Attack Vector

The attack vector requires an attacker to craft a malicious ELF binary with specifically malformed header fields. The exploitation scenario typically involves:

1. An attacker creates a specially crafted ELF file with corrupted section header entries or invalid relocation table references
2. The malicious file is delivered to a target system through various means (email attachment, download, software repository, etc.)
3. When a user or automated system runs readelf against the malicious binary to inspect its contents, the null pointer dereference is triggered
4. The readelf process terminates with a segmentation fault, potentially disrupting analysis workflows or automated security scanning pipelines

The vulnerability can affect security researchers analyzing suspicious binaries, CI/CD pipelines performing binary analysis, and package build systems that validate ELF artifacts.

Detection Methods for CVE-2025-69649

Indicators of Compromise

• Unexpected readelf process crashes with SIGSEGV signals in system logs
• Core dumps generated by readelf containing null pointer dereference stack traces in display_relocations()
• Malformed ELF files with invalid section header indices or corrupted relocation entries in analyzed directories

Detection Strategies

• Monitor for repeated readelf crashes using process monitoring tools or systemd journal analysis
• Implement file integrity monitoring on directories containing ELF binaries to detect introduction of malformed files
• Deploy ELF validation utilities that check header integrity before processing with readelf

Monitoring Recommendations

• Configure crash reporting systems to alert on readelf SIGSEGV events
• Enable audit logging for file access patterns involving ELF binaries from untrusted sources
• Monitor build and analysis pipelines for unexpected process terminations during binary inspection tasks

How to Mitigate CVE-2025-69649

Immediate Actions Required

• Update GNU Binutils to a patched version that includes commit 66a3492ce68e1ae45b2489bd9a815c39ea5d7f66
• Avoid processing ELF binaries from untrusted sources with vulnerable versions of readelf
• Implement sandboxing or containerization for binary analysis workflows to limit the impact of crashes

Patch Information

A fix has been committed to the GNU Binutils Git repository. The patch is available at Sourceware Git Commit 66a3492. Additional technical details about the vulnerability can be found in Sourceware Bug Report #33697. Organizations should update to a version of GNU Binutils that incorporates this fix.

Workarounds

• Use alternative ELF analysis tools such as llvm-readelf from the LLVM project for analyzing untrusted binaries
• Implement pre-processing validation of ELF files using tools like file or custom validators before passing to readelf
• Run readelf in isolated environments (containers, VMs, or sandboxed processes) to prevent crashes from affecting production systems

# Run readelf in a sandboxed environment using firejail
firejail --quiet --net=none readelf -a suspicious_binary.elf

# Alternative: Use LLVM's readelf implementation
llvm-readelf -a suspicious_binary.elf