CVE-2026-2229

Undici has Unhandled Exception in WebSocket Client Due to Invalid server_max_window_bits Validation

Verified by Precogs Threat Research
Last Updated: Mar 18, 2026
Base Score
9.8CRITICAL

Executive Summary

CVE-2026-2229 is a critical severity vulnerability affecting binary-analysis. It is classified as an undisclosed flaw. Ensure your systems and dependencies are patched immediately to mitigate exposure risks.

Precogs AI Insight

"The root cause of this vulnerability lies in within ### Impact, allowing insufficient sanitization protocols during data parsing. When targeted, an adversary might use this to seize control of the underlying infrastructure and pivot to adjacent networks. Precogs Binary SAST/DAST engine uncovers boundary violations in compiled software to prevent unauthorized logical exploitation."

Exploit Probability (EPSS)
Low (0.2%)
Public POC
Available
Exploit Probability
High (84%)
Public POC
Available
Affected Assets
binary analysisNVD Database

What is this vulnerability?

CVE-2026-2229 is categorized as a critical Memory Corruption Vulnerability flaw. Based on our vulnerability intelligence, this issue occurs when the application fails to securely handle untrusted data boundaries.

Impact

The undici WebSocket client is vulnerable to a denial-of-service attack due to improper validation of the server_max_window_bits parameter in.

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 Score9.8 (CRITICAL)
Vector StringN/A
PublishedMarch 13, 2026
Last ModifiedMarch 18, 2026
Related CWEsN/A

Impact on Systems

Remote Code Execution: Adversaries may execute arbitrary code by overwriting memory regions.

Denial of Service: Memory corruption often leads to unrecoverable application crashes.

Information Disclosure: Out-of-bounds reads can expose adjacent memory containing sensitive data.

How to fix this issue?

Implement the following strategic mitigations immediately to eliminate the attack surface.

1. Memory-Safe Languages When possible, migrate parsing logic to memory-safe languages like Rust or Go.

2. Compiler Protections Ensure the binary is compiled with ASLR, DEP/NX, Stack Canaries, and RELRO.

3. Fuzz Testing Implement continuous fuzzing with AddressSanitizer (ASan) in the CI/CD pipeline.

Vulnerability Signature

// Generic Memory Corruption Vector (C/C++)
void process_input(char *user_data, size_t size) \{
    char buffer[256];
    // DANGEROUS: Unbounded memory operation
    memcpy(buffer, user_data, size); // size may exceed 256
    
    // SECURED: Bound-checked operation
    if (size \> sizeof(buffer)) \{
        size = sizeof(buffer);
    \}
    memcpy(buffer, user_data, size);
\}

References and Sources

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: Memory Corruption
void process_data(char *input) {
    char buffer[128];
    // Taint sink: copies without bounds checking
    strcpy(buffer, input);
}

Secure Code Pattern

// ✅ SECURE: Bounded Memory Operations
void process_data(char *input) {
    char buffer[128];
    // 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

Is your system affected?

Precogs AI detects CVE-2026-2229 in compiled binaries, LLMs, and application layers — even without source code access.