CVE-2025-39702
📋 TL;DR
This CVE addresses a timing side-channel vulnerability in the Linux kernel's IPv6 Segment Routing (SR) implementation. Attackers could potentially exploit timing differences in MAC address comparisons to infer sensitive information. This affects all Linux systems using IPv6 Segment Routing.
💻 Affected Systems
- Linux kernel
📦 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...
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
Information disclosure allowing attackers to infer MAC addresses or other sensitive data through timing analysis, potentially enabling further network attacks.
Likely Case
Limited information leakage requiring specialized timing measurements and network access, primarily affecting systems with IPv6 SR enabled.
If Mitigated
Minimal impact if systems don't use IPv6 Segment Routing or have network segmentation limiting attacker access.
🎯 Exploit Status
Exploitation requires precise timing measurements and network access to target system. No public exploits known.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Patches available in stable kernel branches via provided git commits
Vendor Advisory: https://git.kernel.org/stable/c/3b348c9c8d2ca2c67559ffd0e258ae7e1107d4f0
Restart Required: Yes
Instructions:
1. Update Linux kernel to patched version. 2. Check distribution-specific security advisories. 3. Reboot system after kernel update.
🔧 Temporary Workarounds
Disable IPv6 Segment Routing
linuxDisable IPv6 Segment Routing 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
- Disable IPv6 Segment Routing using sysctl commands
- Implement network segmentation to limit access to systems using IPv6 SR
🔍 How to Verify
Check if Vulnerable:
Check kernel version and if IPv6 SR is enabled: sysctl net.ipv6.conf.all.seg6_enabledCheck Version:
uname -rVerify Fix Applied:
Verify kernel version includes the git commit hashes from references, and test MAC comparison functions📡 Detection & Monitoring
Log Indicators:
- Unusual timing patterns in IPv6 packet processing
- Multiple failed MAC comparison attempts
Network Indicators:
- Suspicious timing measurement traffic to IPv6 SR-enabled systems
SIEM Query:
Search for syslog entries related to IPv6 SR errors or unusual timing patterns🔗 References
- https://git.kernel.org/stable/c/3b348c9c8d2ca2c67559ffd0e258ae7e1107d4f0
- https://git.kernel.org/stable/c/3ddd55cf19ed6cc62def5e3af10c2a9df1b861c3
- https://git.kernel.org/stable/c/86b6d34717fe0570afce07ee79b8eeb40341f831
- https://git.kernel.org/stable/c/a458b2902115b26a25d67393b12ddd57d1216aaa
- https://git.kernel.org/stable/c/b3967c493799e63f648e9c7b6cb063aa2aed04e7
- https://git.kernel.org/stable/c/f7878d47560d61e3f370aca3cebb8f42a55b990a
- https://git.kernel.org/stable/c/ff55a452d56490047f5233cc48c5d933f8586884
- https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html
