CVE-2021-47483

Q: What is the severity of CVE-2021-47483?

CVE-2021-47483 has a CVSS score of 7.8 (HIGH). A double-free memory corruption vulnerability in the Linux kernel's regmap subsystem that could lead to system crashes or potential privilege escalation. This affects Linux systems using specific hardware drivers that utilize the regmap framework for device register access.

7.8 HIGH

📋 TL;DR

A double-free memory corruption vulnerability in the Linux kernel's regmap subsystem that could lead to system crashes or potential privilege escalation. This affects Linux systems using specific hardware drivers that utilize the regmap framework for device register access.

💻 Affected Systems

Products:

Linux kernel

Versions: Specific kernel versions containing the vulnerable regcache_rbtree_exit() implementation

Operating Systems: Linux distributions using affected kernel versions

Default Config Vulnerable: ⚠️ Yes

Notes: Requires systems using hardware drivers that utilize the regmap framework (like madera_spi driver mentioned in the trace). Not all Linux systems may be affected depending on hardware configuration.

📦 What is this software?

Linux Kernel by Linux

The Linux Kernel is the core component of the Linux operating system, serving as the critical interface between computer hardware and software processes. As the heart of millions of servers, cloud infrastructure, embedded systems, Android devices, and IoT deployments worldwide, the Linux Kernel mana...

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⚠️ Risk & Real-World Impact

🔴

Worst Case

Kernel panic leading to denial of service, or potential privilege escalation if an attacker can trigger the double-free and execute arbitrary code.

🟠

Likely Case

System crash or kernel panic causing denial of service when the vulnerable code path is triggered during device initialization or operation.

🟢

If Mitigated

No impact if the vulnerable code path is not triggered or if systems are properly patched.

🌐 Internet-Facing: LOW - This requires local access or ability to interact with specific hardware drivers, not directly exploitable over network.

🏢 Internal Only: MEDIUM - Local users or processes could potentially trigger the vulnerability if they have access to affected hardware interfaces.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ✅ No

Complexity: HIGH

Exploitation requires triggering specific error conditions during device initialization, making reliable exploitation challenging.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Kernel versions with the fix from the provided git commits

Vendor Advisory: https://git.kernel.org/stable/c/55e6d8037805b3400096d621091dfbf713f97e83

Restart Required: Yes

Instructions:

1. Update Linux kernel to a version containing the fix. 2. Check your distribution's security advisories for specific patched kernel versions. 3. Reboot the system after kernel update.

🔧 Temporary Workarounds

Disable affected hardware modules

linux

Prevent loading of hardware drivers that use the vulnerable regmap framework

modprobe -r madera_spi
echo 'blacklist madera_spi' >> /etc/modprobe.d/blacklist.conf

🧯 If You Can't Patch

Restrict access to hardware interfaces that could trigger the vulnerable code path
Implement strict process isolation and privilege separation to limit impact if exploitation occurs

🔍 How to Verify

Check if Vulnerable:

Check kernel version and verify if it's before the patched versions referenced in the git commits

Check Version:

uname -r

Verify Fix Applied:

Verify kernel version is updated to a version containing one of the fix commits

📡 Detection & Monitoring

Log Indicators:

Kernel panic messages
KASAN double-free reports in dmesg
System crash logs

Network Indicators:

None - this is a local vulnerability

SIEM Query:

search 'KASAN: double-free' OR 'regcache_rbtree_exit' in kernel logs

📊 Metadata

CVE ID: CVE-2021-47483

CVSS v3 Score: 7.8 (HIGH)

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

CWE: CWE-415

Published: May 22, 2024

Last Updated: January 6, 2025

📋 TL;DR

💻 Affected Systems

📦 What is this software?

Linux Kernel by Linux

Linux Kernel by Linux

Linux Kernel by Linux

Linux Kernel by Linux

Linux Kernel by Linux

Linux Kernel by Linux

Linux Kernel by Linux

Linux Kernel by Linux

Linux Kernel by Linux

Linux Kernel by Linux

Linux Kernel by Linux

Linux Kernel by Linux

Linux Kernel by Linux

Linux Kernel by Linux

⚠️ Risk & Real-World Impact

Worst Case

Likely Case

If Mitigated

🎯 Exploit Status

🛠️ Fix & Mitigation

✅ Official Fix

Instructions:

🔧 Temporary Workarounds

Disable affected hardware modules

🧯 If You Can't Patch

🔍 How to Verify

Check if Vulnerable:

Check Version:

Verify Fix Applied:

📡 Detection & Monitoring

Log Indicators:

Network Indicators:

SIEM Query:

📊 Metadata

🔗 References

📤 Share & Export

🔗 Related Vulnerabilities