CVE-2023-31724 – CVE-2023-31724 is a segmentation fault vulnerab... (How to Fix)

Q: What is the severity of CVE-2023-31724?

CVE-2023-31724 has a CVSS score of 7.8 (HIGH). CVE-2023-31724 is a segmentation fault vulnerability in yasm's do_directive function that can cause denial of service or potentially allow arbitrary code execution. This affects systems using yasm 1.3.0.55.g101bc for assembly code processing. Attackers could exploit this by providing malicious input to the yasm assembler.

📋 TL;DR

CVE-2023-31724 is a segmentation fault vulnerability in yasm's do_directive function that can cause denial of service or potentially allow arbitrary code execution. This affects systems using yasm 1.3.0.55.g101bc for assembly code processing. Attackers could exploit this by providing malicious input to the yasm assembler.

💻 Affected Systems

Products:

yasm

Versions: 1.3.0.55.g101bc

Operating Systems: Linux, Windows, macOS, BSD

Default Config Vulnerable: ⚠️ Yes

Notes: Any system using the vulnerable yasm version to process assembly code is affected

📦 What is this software?

Yasm by Yasm Project

View all CVEs affecting Yasm →

⚠️ Risk & Real-World Impact

🔴

Worst Case

Remote code execution leading to complete system compromise if yasm processes untrusted input

🟠

Likely Case

Denial of service through application crash when processing malformed assembly files

🟢

If Mitigated

Limited impact if yasm only processes trusted, validated assembly code

🌐 Internet-Facing: MEDIUM - yasm is typically used in build systems, not directly internet-facing, but could be exposed via CI/CD pipelines

🏢 Internal Only: MEDIUM - Build systems and development environments using yasm could be affected

🎯 Exploit Status

Public PoC: ⚠️ Yes

Weaponized: LIKELY

Unauthenticated Exploit: ⚠️ Yes

Complexity: LOW

Proof of concept available in GitHub repository showing crash reproduction

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Check yasm GitHub for latest patched version

Vendor Advisory: https://github.com/yasm/yasm/issues/222

Restart Required: No

Instructions:

1. Check current yasm version: yasm --version
2. Update yasm from official repository or source
3. Recompile any projects using yasm with updated version

🔧 Temporary Workarounds

Input validation

all

Validate and sanitize all assembly code input before processing with yasm

Sandbox execution

linux

Run yasm in a sandboxed environment with limited privileges

docker run --read-only --cap-drop=ALL -v /safe/input:/input yasm

🧯 If You Can't Patch

Restrict yasm to process only trusted, pre-validated assembly files
Implement network segmentation to isolate build systems using yasm

🔍 How to Verify

Check if Vulnerable:

Run: yasm --version | grep '1.3.0.55.g101bc'

Check Version:

yasm --version

Verify Fix Applied:

Ensure yasm version is newer than 1.3.0.55.g101bc and test with known crash inputs

📡 Detection & Monitoring

Log Indicators:

Segmentation fault errors in system logs
yasm process crashes
Core dumps from yasm

Network Indicators:

Unusual network traffic to/from build systems
Failed build jobs with crash reports

SIEM Query:

process_name:yasm AND (event_type:crash OR exit_code:139)

📊 Metadata

CVE ID: CVE-2023-31724

CVSS v3 Score: 7.8 (HIGH)

CVSS Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Published: May 17, 2023

Last Updated: January 22, 2025

🔗 References

https://github.com/DaisyPo/fuzzing-vulncollect/tree/main/yasm/SEGV/nasm-pp.c:3570%20in%20do_directive Exploit,Third Party Advisory
https://github.com/yasm/yasm/issues/222 Exploit,Issue Tracking,Third Party Advisory
https://github.com/DaisyPo/fuzzing-vulncollect/tree/main/yasm/SEGV/nasm-pp.c:3570%20in%20do_directive Exploit,Third Party Advisory
https://github.com/yasm/yasm/issues/222 Exploit,Issue Tracking,Third Party Advisory

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