CVE-2020-37239: libbabl Double Free Bypasses Memory Safety
A critical vulnerability, CVE-2020-37239, has been identified in libbabl version 0.1.62, allowing attackers to bypass memory safety checks. The National Vulnerability Database reports this flaw stems from a broken double free detection mechanism. Specifically, libc’s malloc metadata overwrites libbabl’s signature field upon freeing, enabling an attacker to call babl_free() twice on the same pointer without triggering detection.
This signature overwriting in freed chunks is a nasty trick. It means the usual safeguards against double-free errors are nullified, paving the way for potential memory corruption. The National Vulnerability Database assigns a CVSS score of 9.8 (CRITICAL) to this vulnerability, underscoring its severity and the high risk of arbitrary code execution.
For defenders, this is a clear call to action. While specific affected products beyond libbabl 0.1.62 are not detailed by the National Vulnerability Database, any application or system integrating this library version is exposed. The attacker’s calculus here is straightforward: exploit a fundamental memory management flaw for control. Organizations need to identify where libbabl is used in their stacks and prioritize patching or mitigation.
What This Means For You
- If your organization utilizes `libbabl` version 0.1.62, you are exposed to a critical memory corruption vulnerability (CVE-2020-37239) that can lead to remote code execution. Immediately identify all instances of this library in your software dependencies and apply patches or updates to mitigate this risk. This isn't just a crash; it's a direct path to system compromise.
Related ATT&CK Techniques
🛡️ Detection Rules
3 rules · 6 SIEM formats3 detection rules auto-generated for this incident, mapped to MITRE ATT&CK. Sigma YAML is free — export to any SIEM format via the Intel Bot.
CVE-2020-37239: libbabl Double Free Attempt
title: CVE-2020-37239: libbabl Double Free Attempt
id: scw-2026-05-16-ai-1
status: experimental
level: critical
description: |
Detects attempts to exploit CVE-2020-37239 by looking for the specific libbabl version and the invocation of babl_free() which is part of the double free vulnerability. This indicates an attempt to bypass memory safety checks.
author: SCW Feed Engine (AI-generated)
date: 2026-05-16
references:
- https://shimiscyberworld.com/posts/nvd-CVE-2020-37239/
tags:
- attack.initial_access
- attack.t1190
logsource:
category: process_creation
detection:
selection:
Image|contains:
- 'babl-0.1.62'
CommandLine|contains:
- 'babl_free()'
condition: selection
falsepositives:
- Legitimate administrative activity
Source: Shimi's Cyber World · License & reuse
Indicators of Compromise
| ID | Type | Indicator |
|---|---|---|
| CVE-2020-37239 | Memory Corruption | libbabl version 0.1.62 |
| CVE-2020-37239 | Use After Free | Double free vulnerability in babl_free() function |
| CVE-2020-37239 | RCE | Potential code execution via signature overwriting in freed chunks |
Written by SCW Vulnerability Desk
Source & Attribution
| Source Platform | NVD |
| Channel | National Vulnerability Database |
| Published | May 16, 2026 at 19:16 UTC |
This content was AI-rewritten and enriched by Shimi's Cyber World based on the original source. All intellectual property rights remain with the original author.
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