CVE-2026-31668 — AI Deep Analysis Summary

Q: Who is affected? (Versions/Components)

🖥️ **Affected**: Linux Kernel. 🏢 **Vendor**: Linux Foundation. 📅 **Published**: 2026-04-24. ⚠️ **Scope**: All versions using `seg6 lwtunnel` with shared `dst_cache` logic prior to fix.

Q: Is exploitation threshold high? (Auth/Config)

🔓 **Threshold**: LOW. 🌐 **Vector**: Network (AV:N). 🔑 **Auth**: None required (PR:N). 🖱️ **User Interaction**: None (UI:N). 🎯 **Complexity**: Low (AC:L). Easy to exploit remotely.

Q: Is there a public Exp? (PoC/Wild Exploitation)

🚫 **Public Exploit**: None listed in data. 📂 **POCs**: Empty array. 🔍 **Status**: No known wild exploitation yet. But CVSS 9.0 suggests high risk if PoC emerges.

Q: How to self-check? (Features/Scanning)

🔍 **Check**: Scan for Linux Kernel versions. 📡 **Feature**: Look for `seg6` (Segment Routing) and `lwtunnel` usage. 🛠️ **Tool**: Kernel version check against patch commits.

Q: Is it fixed officially? (Patch/Mitigation)

✅ **Fixed**: YES. 📜 **Patches**: 5 kernel commits provided (e.g., `17d87d...`, `84d458...`). 🔗 **Source**: git.kernel.org/stable. Apply these stable kernel updates immediately.

Q: What if no patch? (Workaround)

🚧 **Workaround**: Disable `seg6 lwtunnel` if not needed. 🚫 **Mitigation**: Restrict network access to affected hosts. 🛡️ **Defense**: Use strict firewall rules to limit exposure until patch is applied.

Q: Is it urgent? (Priority Suggestion)

🔥 **Urgency**: CRITICAL. 🚨 **Priority**: P1. CVSS 9.0 (High). Remote, no auth, full impact. Patch immediately upon availability. Do not ignore.

Updated May 06, 2026 CVSS 9.8 · Critical

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Q1What is this vulnerability? (Essence + Consequences)

🚨 **Essence**: Linux Kernel `seg6 lwtunnel` flaw. `dst_cache` is shared between input/output paths. 📉 **Consequences**: Blind reuse of cached routes. Bypasses route lookup.…

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Q2Root Cause? (CWE/Flaw)

🛠️ **Root Cause**: Improper state management in `seg6 lwtunnel`. The `dst_cache` is incorrectly shared across different packet processing paths.…

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Q3Who is affected? (Versions/Components)

🖥️ **Affected**: Linux Kernel. 🏢 **Vendor**: Linux Foundation. 📅 **Published**: 2026-04-24. ⚠️ **Scope**: All versions using `seg6 lwtunnel` with shared `dst_cache` logic prior to fix.

Q4What can hackers do? (Privileges/Data)

🕵️ **Hacker Actions**: Bypass routing security checks. 📦 **Impact**: Full Control. **Confidentiality**: High. **Integrity**: High. **Availability**: High.…

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Q5Is exploitation threshold high? (Auth/Config)

🔓 **Threshold**: LOW. 🌐 **Vector**: Network (AV:N). 🔑 **Auth**: None required (PR:N). 🖱️ **User Interaction**: None (UI:N). 🎯 **Complexity**: Low (AC:L). Easy to exploit remotely.

Q6Is there a public Exp? (PoC/Wild Exploitation)

🚫 **Public Exploit**: None listed in data. 📂 **POCs**: Empty array. 🔍 **Status**: No known wild exploitation yet. But CVSS 9.0 suggests high risk if PoC emerges.

Q7How to self-check? (Features/Scanning)

🔍 **Check**: Scan for Linux Kernel versions. 📡 **Feature**: Look for `seg6` (Segment Routing) and `lwtunnel` usage. 🛠️ **Tool**: Kernel version check against patch commits.

Q8Is it fixed officially? (Patch/Mitigation)

✅ **Fixed**: YES. 📜 **Patches**: 5 kernel commits provided (e.g., `17d87d...`, `84d458...`). 🔗 **Source**: git.kernel.org/stable. Apply these stable kernel updates immediately.

Q9What if no patch? (Workaround)

🚧 **Workaround**: Disable `seg6 lwtunnel` if not needed. 🚫 **Mitigation**: Restrict network access to affected hosts. 🛡️ **Defense**: Use strict firewall rules to limit exposure until patch is applied.

Q10Is it urgent? (Priority Suggestion)

🔥 **Urgency**: CRITICAL. 🚨 **Priority**: P1. CVSS 9.0 (High). Remote, no auth, full impact. Patch immediately upon availability. Do not ignore.

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