CVE-2024-35821 – This Linux kernel vulnerability in the UBIFS fi... (How to Fix)

Q: What is the severity of CVE-2024-35821?

CVE-2024-35821 has a CVSS score of 5.5 (MEDIUM). This Linux kernel vulnerability in the UBIFS filesystem allows concurrent readers to see stale data when reading from page cache. It affects systems using UBIFS on flash storage with unpatched Linux kernels. The race condition occurs during file write operations.

📋 TL;DR

This Linux kernel vulnerability in the UBIFS filesystem allows concurrent readers to see stale data when reading from page cache. It affects systems using UBIFS on flash storage with unpatched Linux kernels. The race condition occurs during file write operations.

💻 Affected Systems

Products:

Linux kernel

Versions: Specific affected versions not specified in CVE, but patches exist in stable kernel trees

Operating Systems: Linux distributions using affected kernel versions

Default Config Vulnerable: ⚠️ Yes

Notes: Only affects systems using UBIFS (Unsorted Block Image File System), typically on flash storage devices like SSDs or embedded systems.

📦 What is this software?

Debian Linux by Debian

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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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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...

Learn more about Linux Kernel →

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...

Learn more about Linux Kernel →

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...

Learn more about Linux Kernel →

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...

Learn more about Linux Kernel →

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...

Learn more about Linux Kernel →

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...

Learn more about Linux Kernel →

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...

Learn more about Linux Kernel →

⚠️ Risk & Real-World Impact

🔴

Worst Case

Data corruption or information disclosure where sensitive data from previously freed pages could be exposed to unauthorized processes.

🟠

Likely Case

Application crashes or data inconsistencies when processes read outdated file content during concurrent operations.

🟢

If Mitigated

Minor performance impact with proper kernel isolation and filesystem permissions limiting exposure.

🌐 Internet-Facing: LOW - Requires local filesystem access and specific UBIFS usage patterns.

🏢 Internal Only: MEDIUM - Local users or processes could exploit this to read stale data or cause application instability.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ✅ No

Complexity: MEDIUM

Requires local access and timing precision to trigger the race condition. No known public exploits.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Patched in stable kernel releases via commits referenced in CVE

Vendor Advisory: https://git.kernel.org/stable/c/142d87c958d9454c3cffa625fab56f3016e8f9f3

Restart Required: Yes

Instructions:

1. Update Linux kernel to patched version from your distribution's repositories. 2. Reboot system to load new kernel. 3. Verify kernel version after reboot.

🔧 Temporary Workarounds

Avoid UBIFS usage

linux

Use alternative filesystems if UBIFS is not required for your use case

Restrict filesystem access

linux

Limit which users and processes can access UBIFS-mounted directories

chmod 700 /mount/point
setfacl -m u:username:rx /mount/point

🧯 If You Can't Patch

Implement strict access controls on UBIFS-mounted directories
Monitor system logs for filesystem errors or application crashes related to UBIFS operations

🔍 How to Verify

Check if Vulnerable:

Check if using UBIFS: 'mount | grep ubifs' and check kernel version against patched releases

Check Version:

uname -r

Verify Fix Applied:

Verify kernel version after update and ensure UBIFS is functioning normally

📡 Detection & Monitoring

Log Indicators:

UBIFS error messages in dmesg or system logs
Application crashes when reading/writing UBIFS files

Network Indicators:

None - local filesystem vulnerability

SIEM Query:

source="kernel" AND "UBIFS" AND ("error" OR "warning")

📊 Metadata

CVE ID: CVE-2024-35821

CVSS v3 Score: 5.5 (MEDIUM)

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

CWE: CWE-772

Published: May 17, 2024

Last Updated: December 23, 2025

🔗 References

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🔗 Related Vulnerabilities

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