CVE-2025-37749

Q: What is the severity of CVE-2025-37749?

CVE-2025-37749 has a CVSS score of 7.1 (HIGH). This CVE describes an out-of-bounds read vulnerability in the Linux kernel's PPP (Point-to-Point Protocol) implementation. When processing short or empty PPPoE packets, the ppp_sync_txmung function could access memory beyond the allocated buffer, potentially leading to kernel crashes or information disclosure. Systems using PPP/PPPoE networking are affected.

7.1 HIGH

📋 TL;DR

This CVE describes an out-of-bounds read vulnerability in the Linux kernel's PPP (Point-to-Point Protocol) implementation. When processing short or empty PPPoE packets, the ppp_sync_txmung function could access memory beyond the allocated buffer, potentially leading to kernel crashes or information disclosure. Systems using PPP/PPPoE networking are affected.

💻 Affected Systems

Products:

Linux kernel

Versions: Specific affected versions not specified in CVE, but patches available for multiple stable branches

Operating Systems: Linux distributions using vulnerable kernel versions

Default Config Vulnerable: ✅ No

Notes: Only affects systems with PPP/PPPoE enabled and configured

📦 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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⚠️ Risk & Real-World Impact

🔴

Worst Case

Kernel panic leading to system crash and denial of service, or potential information disclosure from kernel memory

🟠

Likely Case

System crash or instability when processing malformed PPPoE packets

🟢

If Mitigated

No impact if patched or PPP/PPPoE not in use

🌐 Internet-Facing: MEDIUM - Requires PPP/PPPoE exposure to internet, which is less common than other protocols

🏢 Internal Only: LOW - PPP/PPPoE typically used in specific network configurations, not default

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ⚠️ Yes

Complexity: MEDIUM

Exploitation requires sending specially crafted PPPoE packets to vulnerable systems

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Multiple stable kernel versions with commits: 1f6eb9fa87a7, 529401c8f12e, 6e8a6bf43cea, 99aa698dec34, aabc6596ffb3

Vendor Advisory: https://git.kernel.org/stable/c/1f6eb9fa87a781d5370c0de7794ae242f1a95ee5

Restart Required: Yes

Instructions:

1. Update Linux kernel to patched version 2. Reboot system 3. Verify kernel version after reboot

🔧 Temporary Workarounds

Disable PPP/PPPoE

linux

If PPP/PPPoE is not required, disable the modules

modprobe -r pppoe
modprobe -r pppox
modprobe -r ppp_generic

🧯 If You Can't Patch

Implement network filtering to block PPPoE traffic from untrusted sources
Monitor systems for crashes or instability related to PPP/PPPoE services

🔍 How to Verify

Check if Vulnerable:

Check if PPP/PPPoE modules are loaded: lsmod | grep -E 'ppp|pppoe'

Check Version:

uname -r

Verify Fix Applied:

Check kernel version against patched versions and verify PPP/PPPoE functionality

📡 Detection & Monitoring

Log Indicators:

Kernel panic logs
System crash dumps
PPP/PPPoE service failures

Network Indicators:

Unusual PPPoE packet patterns
Multiple short/empty PPPoE packets

SIEM Query:

source="kernel" AND ("panic" OR "oops") AND ("ppp" OR "pppoe")

📊 Metadata

CVE ID: CVE-2025-37749

CVSS v3 Score: 7.1 (HIGH)

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

CWE: CWE-125

EPSS Score: 0.02% exploit probability (4.3th percentile)

Published: May 1, 2025

Last Updated: November 4, 2025

📋 TL;DR

💻 Affected Systems

📦 What is this software?

Debian Linux by Debian

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 PPP/PPPoE

🧯 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