CVE-2021-34448

Out-of-bounds Write in Scripting Engine Memory Corruption Vulnerability

Verified by Precogs Threat Research
Last Updated: Oct 29, 2025
Base Score
6.8MEDIUM

Executive Summary

CVE-2021-34448 is a medium severity vulnerability affecting binary-analysis. It is classified as Out-of-bounds Write. This vulnerability is actively being exploited in the wild.

Precogs AI Insight

"A scripting engine memory corruption vulnerability allows remote code execution in Microsoft Edge and Internet Explorer. Attackers exploit JIT compilation errors to bypass sandbox constraints. Precogs Binary Analysis identifies hazardous input validation during dynamic recompilation."

Exploit Probability (EPSS)
Low (2.0%)
Public POC
Available
Exploit Probability
Low (<10%)
Public POC
Actively Exploited
Affected Assets
binary analysisCWE-787

What is this vulnerability?

CVE-2021-34448 is categorized as a medium Out-of-bounds Write flaw with a CVSS base score of 6.8. Based on our vulnerability intelligence, this issue occurs when the application fails to securely handle untrusted data boundaries.

Scripting Engine Memory Corruption Vulnerability

This architectural defect enables adversaries to bypass intended security controls, directly manipulating the application's execution state or data layer. Immediate strategic intervention is required.

Risk Assessment

MetricValue
CVSS Base Score6.8 (MEDIUM)
Vector StringCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N
PublishedJuly 16, 2021
Last ModifiedOctober 29, 2025
Related CWEsCWE-787, CWE-787

Impact on Systems

Remote Code Execution: Attackers can overwrite the instruction pointer to redirect execution to malicious shellcode.

Memory Corruption: Overwriting adjacent memory regions can corrupt critical application state, leading to privilege escalation.

Denial of Service: Triggering segmentation faults results in immediate disruption of critical systems.

How to Fix and Mitigate CVE-2021-34448

  1. Apply Vendor Patches Immediately: This vulnerability is listed in CISA's Known Exploited Vulnerabilities catalog. Apply updates per vendor instructions.
  2. Verify Patch Deployment: Confirm all instances are updated using Precogs continuous monitoring.
  3. Review Audit Logs: Investigate historical access logs for indicators of compromise related to this attack surface.
  4. Implement Defense-in-Depth: Deploy WAF rules, network segmentation, and endpoint detection to limit blast radius.

Defending with Precogs AI

A scripting engine memory corruption vulnerability allows remote code execution in Microsoft Edge and Internet Explorer. Attackers exploit JIT compilation errors to bypass sandbox constraints. Precogs Binary Analysis identifies hazardous input validation during dynamic recompilation.

Use Precogs to continuously scan your codebase, binaries, APIs, and infrastructure for this vulnerability class and related attack patterns. Our AI-powered detection engine combines static analysis with threat intelligence to identify exploitable weaknesses before attackers do.

Start scanning with Precogs →

Vulnerability Code Signature

Attack Data Flow

StageDetail
SourceNetwork packet or file input
VectorData exceeds the allocated buffer bounds during a copy operation
Sinkstrcpy(), memcpy(), or pointer arithmetic
ImpactMemory corruption, Remote Code Execution (RCE)

Vulnerable Code Pattern

// ❌ VULNERABLE: Out-of-bounds write
void process_data(char *input) {
    char buffer[64];
    // Taint sink: copies without bounds checking
    strcpy(buffer, input);
}

Secure Code Pattern

// ✅ SECURE: Bounded copy
void process_data(char *input) {
    char buffer[64];
    // Sanitized boundary check
    strncpy(buffer, input, sizeof(buffer) - 1);
    buffer[sizeof(buffer) - 1] = '\0';
}

How Precogs Detects This

Precogs Binary SAST engine explicitly uncovers memory boundary violations and unsafe memory management functions in compiled binaries.\n

Related Vulnerabilitiesvia CWE-787

Is your system affected?

Precogs AI detects CVE-2021-34448 in compiled binaries, LLMs, and application layers — even without source code access.