CVE-2024-37371: MIT Kerberos 5 Use-After-Free Vulnerability

CVE-2024-37371 Overview

In MIT Kerberos 5 (aka krb5) before 1.21.3, an attacker can cause invalid memory reads during GSS message token handling by sending message tokens with invalid length fields.

Critical Impact
This vulnerability allows attackers to execute denial of service attacks with high impact on availability and confidentiality.

Affected Products

mit kerberos_5
debian debian_linux

Discovery Timeline

Not Available
Not Available
Not Available
2024-06-28T23:15:11.603 - CVE CVE-2024-37371 published to NVD
2025-11-03T21:16:13.997 - Last updated in NVD database

Technical Details for CVE-2024-37371

Vulnerability Analysis

This vulnerability exists due to improper handling of invalid length fields in GSS message tokens, leading to out-of-bounds read errors. Attackers can exploit this through specially crafted message tokens, affecting memory integrity and potentially leading to application crashes.

Root Cause

The root cause is the improper validation of length fields in message tokens within the GSS protocol handling code.

Attack Vector

The attack vector is network-based, allowing remote exploitation of the vulnerability without prior authentication.

// Example exploitation code (sanitized)
#include <stdio.h>
#include <string.h>

void process_message_token(char *token, int length) {
    // Potentially unsafe memory read
    char buffer[256];
    if (length < sizeof(buffer)) {
        memcpy(buffer, token, length);
    } else {
        printf("Token length exceeds buffer size\n");
    }
}

int main() {
    char malicious_token[] = "malicious_data_with_invalid_length";
    process_message_token(malicious_token, 300); // Incorrect length
    return 0;
}

Detection Methods for CVE-2024-37371

Indicators of Compromise

Unusual application crashes
Unexpected memory access violations
Log entries indicating invalid message token processing

Detection Strategies

Utilize intrusion detection systems (IDS) to monitor network traffic for malformed GSS tokens. Anomalies in token sizes can indicate potential exploitation attempts.

Monitoring Recommendations

Regularly inspect system logs for segmentation faults originating from the krb5 daemon processes and validate network traffic for anomalous packet sizes or patterns.

How to Mitigate CVE-2024-37371

Immediate Actions Required

Update MIT Kerberos 5 to the latest version
Restrict network exposure of affected services
Monitor network traffic for unusual token sizes

Patch Information

For patch details, refer to the GitHub commit addressing the issue.

Workarounds

Limiting access to GSS API services, deploying application-level defenses to sanitize token lengths before processing.

bash

# Configuration example
iptables -A INPUT -p tcp --dport 88 -m state --state NEW,ESTABLISHED -j ACCEPT
iptables -A OUTPUT -p tcp --sport 88 -m state --state ESTABLISHED -j ACCEPT