CVE-2022-36227: Libarchive Use-After-Free Vulnerability

CVE-2022-36227 Overview

CVE-2022-36227 is a NULL Pointer Dereference vulnerability affecting libarchive versions prior to 3.6.2. The vulnerability exists because the software does not check for an error after calling the calloc function, which can return a NULL pointer if the function fails. This leads to a resultant NULL pointer dereference condition.

While the security impact is debated among researchers—with some noting that in rare circumstances where NULL is equivalent to the 0x0 memory address and privileged code can access it, writing or reading memory may be possible, potentially leading to code execution—the vulnerability nonetheless represents a significant stability and security concern for applications utilizing libarchive for archive processing operations.

Critical Impact

This NULL pointer dereference vulnerability in libarchive can cause application crashes and potential denial of service. In rare edge cases involving privileged code accessing 0x0 memory, code execution may be theoretically possible.

Affected Products

• libarchive versions before 3.6.2
• Debian Linux 10.0
• Fedora 37
• Splunk Universal Forwarder (multiple versions including 9.1.0)

Discovery Timeline

• 2022-11-22 - CVE-2022-36227 published to NVD
• 2025-11-03 - Last updated in NVD database

Technical Details for CVE-2022-36227

Vulnerability Analysis

The vulnerability stems from improper error handling in libarchive's memory allocation routines. When calloc is called to allocate memory for archive operations, the return value is not validated before use. The calloc function can fail and return NULL under various conditions including memory exhaustion, extremely large allocation requests, or system resource constraints.

When this NULL pointer is subsequently dereferenced in the code path, it triggers undefined behavior. On most modern operating systems with memory protection, this results in a segmentation fault and program termination. However, the CVE description notes that in specialized environments where NULL maps to accessible memory at address 0x0, more severe consequences could theoretically occur.

The vulnerable code pattern exists in the archive write functionality, specifically in archive_write.c. Applications that process untrusted archive files or operate under memory-constrained conditions are at elevated risk.

Root Cause

The root cause is a missing NULL check after the calloc memory allocation call (CWE-476: NULL Pointer Dereference). The software assumes that memory allocation will always succeed and proceeds to use the returned pointer without validation. This violates secure coding practices that mandate checking return values from functions that can fail.

The issue is compounded by the fact that libarchive is widely used as a library in numerous applications and operating systems, amplifying the potential attack surface.

Attack Vector

This vulnerability is exploitable over the network without requiring authentication or user interaction. An attacker could potentially trigger the vulnerability by:

1. Providing a specially crafted archive file that causes libarchive to attempt large or numerous memory allocations
2. Exploiting memory pressure conditions on the target system to cause calloc to fail
3. Targeting applications that process archives from untrusted sources

The network attack vector makes this vulnerability particularly concerning for services that automatically process uploaded archives or extract files from remote sources.

The vulnerability manifests when calloc fails and returns NULL, but the code continues execution without validating this return value. The subsequent operations on the NULL pointer cause the crash or undefined behavior. For technical details, see the GitHub code reference and GitHub Issue #1754.

Detection Methods for CVE-2022-36227

Indicators of Compromise

• Application crashes or segmentation faults in processes using libarchive during archive operations
• Unexpected service terminations when processing archive files
• Core dumps containing references to libarchive functions and NULL pointer access
• Repeated failures in archive extraction or creation workflows

Detection Strategies

• Monitor for segmentation fault signals (SIGSEGV) in applications linked against libarchive
• Implement version checking for libarchive installations to identify versions prior to 3.6.2
• Deploy memory monitoring to detect abnormal allocation patterns that could trigger the vulnerability
• Use SentinelOne's behavioral detection to identify crash patterns consistent with NULL pointer dereference exploitation

Monitoring Recommendations

• Enable crash reporting and core dump collection for applications using libarchive
• Monitor system logs for repeated application failures during archive processing
• Implement application-level health checks for services that depend on libarchive functionality
• Track resource utilization to identify potential memory exhaustion attacks that could trigger the vulnerability

How to Mitigate CVE-2022-36227

Immediate Actions Required

• Update libarchive to version 3.6.2 or later immediately
• Identify all applications and services in your environment that depend on libarchive
• Prioritize patching systems that process archives from untrusted sources
• Apply vendor-specific patches from Debian, Fedora, Gentoo, and Splunk as applicable

Patch Information

The vulnerability is fixed in libarchive version 3.6.2 and later. Multiple Linux distributions have released security updates:

• Debian: Security advisory available for Debian LTS - see Debian LTS Announcement January 2023 and Debian LTS Announcement November 2024
• Fedora: Package update released for Fedora 37 - see Fedora Package Announcement
• Gentoo: Security advisory GLSA 2023-09-14 issued - see Gentoo GLSA 2023-09-14
• Splunk: Update Universal Forwarder to patched versions

Consult the Gentoo Bug Report #882521 for additional technical details.

Workarounds

• Implement input validation to limit archive sizes and prevent processing of extremely large archives
• Deploy resource limits (ulimits) to prevent memory exhaustion scenarios that could trigger allocation failures
• Isolate archive processing in sandboxed environments to contain potential exploitation
• Consider using application-level memory overcommit settings to reduce calloc failure likelihood in controlled environments

# Configuration example
# Check installed libarchive version
bsdtar --version

# Update libarchive on Debian/Ubuntu
sudo apt update && sudo apt install libarchive-tools libarchive13

# Update libarchive on Fedora
sudo dnf update libarchive

# Update libarchive on Gentoo
sudo emerge --sync && sudo emerge -uDN app-arch/libarchive

# Set resource limits to reduce exploitation risk
ulimit -v 2097152  # Limit virtual memory to 2GB