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CVE-2026-43186
critical
CVSS 9.8
Vulnerability in c (CVE-2026-43186)
Summary
vulnerability in c (CVE-2026-43186). Successful exploitation can lead to full system takeover.
AI summary openai / gpt-4o
A critical vulnerability in the IPv6 functionality of the Linux kernel has been discovered. If exploited, an attacker can destabilize the system and compromise critical data. Similar to past incidents like "Heartbleed" or "Log4Shell," this vulnerability risks causing memory overflow. Companies should promptly update their systems and apply the available patch to prevent exploitation.
The Linux kernel's __ioam6_fill_trace_data() function had a heap buffer overflow issue, which trusted the trace->nodelen field on the receive path without consistency checks, allowing crafted packets to cause memory corruption and kernel panic. The patch introduces a shared helper ioam6_trace_compute_nodelen() to enforce consistency and prevent misuse. Administrators should apply the patch promptly to mitigate this vulnerability.
❓ What is the problem
Heap buffer overflow in __ioam6_fill_trace_data() within the Linux kernel's IPv6 function.
📍 Affected scope
__ioam6_fill_trace_data() function on the receive path in the Linux kernel.
🔥 Severity
Critical severity (CVSS 9.8), allowing remote exploitation, no privileges required.
🔧 How to fix
Apply the provided patch introducing ioam6_trace_compute_nodelen() for consistency checks.
🛡️ Workaround
No specific workaround, immediate patching is advised.
🔍 Detection
Check for packets with inconsistent nodelen and type fields using monitoring tools.
Related past incidents Similar incidents extracted from past CVEs
Heartbleed allowed attackers to read memory from servers using OpenSSL, similar in its memory-related vulnerability nature.
Log4Shell was an RCE exploit through logging, emphasizing the criticality of memory safety.
If this happens at your company Expected impact per business scenario
📌 In cloud environments where Linux servers are prevalent
Attacker could cause denial of service or data compromise across multiple tenants.
📌 In data centers heavily relying on IPv6 for internal communications
Internal network disruptions could occur, affecting business-critical applications.
📌 In organizations with high-security requirements such as finance or healthcare
Data integrity and confidentiality could be severely compromised.
Recommended action
Immediately apply the security patch to all vulnerable Linux kernel versions.
Response Actions (7 steps)
Concrete steps and command examples for SOC/SRE teams to execute in order
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1Identify exposure identify
grep -r 'c' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で `c` を grep し、稼働しているサービス・バージョンを把握する。
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7Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番では Step 3 と同じログクエリでアラート再発が無いか継続監視。
References
- web https://git.kernel.org/stable/c/0591d6509c2ff13f09ea2998434aba0c0472e978
- web https://git.kernel.org/stable/c/632d233cf2e64a46865ae2c064ae3c9df7c8864f
- web https://git.kernel.org/stable/c/6db8b56eed62baacaf37486e83378a72635c04cc
- web https://git.kernel.org/stable/c/e90346a2f1e8917d5760a44a1f61c44e3b36d96b
- web https://git.kernel.org/stable/c/ea3632aefc04205436868541638e26f4a74d5637
- web https://git.kernel.org/stable/c/f4d9d4b8fd839719d564651671e24c62c545c23b
- web https://git.kernel.org/stable/c/fb3c662fafebc5b9d74417ed1de8759f6bb72143
- web https://nvd.nist.gov/vuln/detail/CVE-2026-43186
- web https://github.com/advisories/GHSA-8x8h-4g2v-qpf2