CVE-2024-42040
📋 TL;DR
This CVE describes a buffer overflow vulnerability in U-Boot's DHCP client implementation that allows an attacker on the local network to leak 4-32 bytes of memory via crafted DHCP responses. The vulnerability affects all platforms running U-Boot from its initial 2002 commit up to the present. This could expose sensitive information from device memory to network attackers.
💻 Affected Systems
- DENEX U-Boot
⚠️ Manual Verification Required
This CVE does not have specific version information in our database, so automatic vulnerability detection cannot determine if your system is affected.
Why? The CVE database entry doesn't specify which versions are vulnerable (no version ranges provided by the vendor/NVD).
🔒 Custom verification scripts are available for registered users. Sign up free to download automated test scripts.
- Review the CVE details at NVD
- Check vendor security advisories for your specific version
- Test if the vulnerability is exploitable in your environment
- Consider updating to the latest version as a precaution
⚠️ Risk & Real-World Impact
Worst Case
An attacker could leak sensitive memory contents including cryptographic keys, passwords, or other secrets stored in device memory, potentially enabling further attacks or credential theft.
Likely Case
Memory disclosure of random or structured data from the device's memory space, which could be used for information gathering or as part of a multi-stage attack chain.
If Mitigated
Limited impact if network segmentation prevents untrusted DHCP servers or if the leaked memory contains non-sensitive data.
🎯 Exploit Status
Exploitation requires attacker to be on the same local network and able to send DHCP responses. The advisory includes technical details that could be used to create exploits.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check latest U-Boot releases for fixes
Vendor Advisory: https://github.com/u-boot/u-boot/tags
Restart Required: Yes
Instructions:
1. Update U-Boot to latest version from official repository. 2. Rebuild and flash the bootloader to affected devices. 3. Verify the fix by checking for updated net/bootp.c implementation.
🔧 Temporary Workarounds
Disable DHCP client
allConfigure devices to use static IP addresses instead of DHCP
Set CONFIG_BOOTP=n in U-Boot configuration
Network segmentation
allIsolate devices using U-Boot from untrusted networks
🧯 If You Can't Patch
- Implement strict network segmentation to prevent untrusted DHCP servers
- Monitor network for suspicious DHCP traffic and implement DHCP snooping
🔍 How to Verify
Check if Vulnerable:
Check U-Boot version and verify if net/bootp.c contains the vulnerable code from the initial commit up to patched versionsCheck Version:
printenv version (in U-Boot) or check U-Boot build configurationVerify Fix Applied:
Verify U-Boot version is updated and check that net/bootp.c has proper bounds checking for DHCP responses📡 Detection & Monitoring
Log Indicators:
- Unusual DHCP response patterns
- Memory access errors in boot logs
Network Indicators:
- Suspicious DHCP traffic from untrusted sources
- DHCP responses with crafted options
SIEM Query:
dhcp.response AND (src_ip NOT IN trusted_dhcp_servers)