CVE-2025-38310 – A memory validation vulnerability in the Linux ... (How to Fix)

Q: What is the severity of CVE-2025-38310?

CVE-2025-38310 has a CVSS score of 5.5 (MEDIUM). A memory validation vulnerability in the Linux kernel's Segment Routing over IPv6 (seg6) subsystem allows reading uninitialized memory when user space provides mismatched nexthop address lengths. This affects Linux systems using IPv6 segment routing functionality. Attackers could potentially leak kernel memory contents or cause system instability.

📋 TL;DR

A memory validation vulnerability in the Linux kernel's Segment Routing over IPv6 (seg6) subsystem allows reading uninitialized memory when user space provides mismatched nexthop address lengths. This affects Linux systems using IPv6 segment routing functionality. Attackers could potentially leak kernel memory contents or cause system instability.

💻 Affected Systems

Products:

Linux kernel

Versions: Specific affected versions not specified in CVE, but references indicate multiple stable kernel versions

Operating Systems: Linux distributions using vulnerable kernel versions

Default Config Vulnerable: ✅ No

Notes: Only vulnerable if IPv6 segment routing (seg6) functionality is enabled and configured. Most default configurations are not affected.

📦 What is this software?

Debian Linux by Debian

View all CVEs affecting Debian Linux →

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 →

⚠️ Risk & Real-World Impact

🔴

Worst Case

Kernel memory disclosure leading to information leakage, potential privilege escalation if sensitive data is exposed, or kernel panic causing denial of service.

🟠

Likely Case

Information disclosure of kernel memory contents, potentially exposing sensitive data structures or causing system instability.

🟢

If Mitigated

Minimal impact with proper access controls and network segmentation limiting exposure to untrusted users.

🌐 Internet-Facing: LOW - Requires IPv6 segment routing configuration and network access to specific kernel interfaces.

🏢 Internal Only: MEDIUM - Internal attackers with network access to affected interfaces could exploit this vulnerability.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ✅ No

Complexity: MEDIUM

Exploitation requires network access to the seg6 subsystem and knowledge of the specific interface. No public exploits known at this time.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Kernel versions containing commits: 668923c474608dd9ebce0fbcc41bd8a27aa73dd6, 7632fedb266d93ed0ed9f487133e6c6314a9b2d1, cd4cd09810211fa23609c5c1018352e9e1cd8e5a, cef33a86bcb04ecf4dc10c56f6c42ee9d1c54bac, d2507aeea45b3c5aa24d5daae0cf3db76895c0b7

Vendor Advisory: https://git.kernel.org/stable/c/668923c474608dd9ebce0fbcc41bd8a27aa73dd6

Restart Required: Yes

Instructions:

1. Update Linux kernel to patched version. 2. Check distribution-specific security advisories. 3. Reboot system to load new kernel.

🔧 Temporary Workarounds

Disable IPv6 Segment Routing

linux

Disable seg6 functionality if not required

sysctl -w net.ipv6.conf.all.seg6_enabled=0
sysctl -w net.ipv6.conf.default.seg6_enabled=0

🧯 If You Can't Patch

Restrict network access to systems using IPv6 segment routing
Implement strict network segmentation and firewall rules to limit exposure

🔍 How to Verify

Check if Vulnerable:

Check kernel version and seg6 configuration: sysctl net.ipv6.conf.all.seg6_enabled

Check Version:

uname -r

Verify Fix Applied:

Verify kernel version contains the fix commits or check with distribution-specific security tools

📡 Detection & Monitoring

Log Indicators:

Kernel logs showing memory access violations
System logs related to IPv6 segment routing

Network Indicators:

Unusual IPv6 segment routing traffic patterns
Network probes targeting seg6 interfaces

SIEM Query:

source="kernel" AND ("seg6" OR "nexthop") AND ("error" OR "warning" OR "violation")

📊 Metadata

CVE ID: CVE-2025-38310

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

EPSS Score: 0.02% exploit probability (4.2th percentile)

Published: July 10, 2025

Last Updated: December 19, 2025

🔗 References

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