CVE-2021-27357 – CVE-2021-27357 is a buffer overflow vulnerabili... (How to Fix)

📋 TL;DR

CVE-2021-27357 is a buffer overflow vulnerability in RIOT-OS's RPL routing protocol implementation that allows remote attackers to execute arbitrary code or cause denial of service. This affects devices running RIOT-OS 2020.01 with RPL routing enabled, particularly IoT and embedded systems.

💻 Affected Systems

Products:

RIOT-OS

Versions: 2020.01

Operating Systems: RIOT-OS

Default Config Vulnerable: ⚠️ Yes

Notes: Only vulnerable when RPL routing is enabled (GNRC_RPL_DEFAULT enabled in build configuration)

📦 What is this software?

Riot by Riot Os

View all CVEs affecting Riot →

⚠️ Risk & Real-World Impact

🔴

Worst Case

Remote code execution leading to complete device compromise, data exfiltration, or device becoming part of botnet

🟠

Likely Case

Denial of service causing device crashes and network disruption

🟢

If Mitigated

Limited impact if RPL routing is disabled or network segmentation isolates vulnerable devices

🌐 Internet-Facing: HIGH - Exploitable remotely without authentication via network packets

🏢 Internal Only: HIGH - Exploitable from any network segment with access to vulnerable devices

🎯 Exploit Status

Public PoC: ⚠️ Yes

Weaponized: LIKELY

Unauthenticated Exploit: ⚠️ Yes

Complexity: LOW

Proof-of-concept available in GitHub issues; exploitation requires sending crafted RPL control messages

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: 2021.01 and later

Vendor Advisory: https://github.com/RIOT-OS/RIOT/issues/16018

Restart Required: Yes

Instructions:

1. Update RIOT-OS to version 2021.01 or later
2. Rebuild firmware with updated source
3. Flash updated firmware to affected devices
4. Verify RPL routing functionality after update

🔧 Temporary Workarounds

Disable RPL Routing

all

Disable RPL routing protocol in build configuration to prevent exploitation

Set GNRC_RPL_DEFAULT=0 in Makefile or build configuration

Network Segmentation

all

Isolate devices using RPL routing to trusted network segments only

🧯 If You Can't Patch

Implement strict network ACLs to block RPL control messages from untrusted sources
Deploy network intrusion detection systems to monitor for RPL protocol anomalies

🔍 How to Verify

Check if Vulnerable:

Check if running RIOT-OS 2020.01 with RPL routing enabled (GNRC_RPL_DEFAULT=1)

Check Version:

Check RIOT_VERSION in source code or firmware metadata

Verify Fix Applied:

Verify RIOT-OS version is 2021.01 or later and RPL routing functions normally

📡 Detection & Monitoring

Log Indicators:

Device crashes, abnormal RPL protocol messages, memory corruption errors

Network Indicators:

Unusual RPL control message patterns, malformed RPL packets

SIEM Query:

Search for: (RIOT-OS OR RPL) AND (buffer_overflow OR crash OR CVE-2021-27357)

📊 Metadata

CVE ID: CVE-2021-27357

CVSS v3 Score: 9.8 (CRITICAL)

CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CWE: CWE-120

Published: April 6, 2021

Last Updated: November 21, 2024

🔗 References

https://github.com/RIOT-OS/RIOT/issues/16018 Third Party Advisory
https://github.com/RIOT-OS/RIOT/issues/16018 Third Party Advisory

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🔗 Related Vulnerabilities

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