Vulnerability in arduino-esp32 (CVE-2026-42854)
Summary
Vulnerability in arduino-esp32 (CVE-2026-42854). Successful exploitation can lead to full system takeover. Mitigation: upgrade to 3.3.8 or later.
Original description
The description as published by the source.
arduino-esp32 is an Arduino core for the ESP32, ESP32-S2, ESP32-S3, ESP32-C3, ESP32-C6 and ESP32-H2 microcontrollers. Prior to 3.3.8, the WebServer multipart form parser in arduino-esp32 allocates a Variable Length Array (VLA) on the stack whose size is derived from an attacker-controlled HTTP header field (Content-Type: multipart/form-data; boundary=...) without enforcing any length limit. Sending a boundary string longer than ~8000 characters overflows the 8192-byte task stack of the loopTask, causing a crash and potential remote code execution. This vulnerability is fixed in 3.3.8.
Source: NIST National Vulnerability Database NVD
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-42854 has been found in arduino-esp32.
Successful exploitation can lead to full system takeover. CVSS score: 9.8/10.
What to do: upgrade arduino-esp32 to 3.3.8 or later.
If unsure, ask your IT team or search "arduino-esp32 CVE-2026-42854" on the vendor's site.
CVE-2026-42854 (arduino-esp32) — CWE-121 / CVSS v3 9.8
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Patched: 3.3.8 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
A vulnerability (CWE-121) exists in arduino-esp32.
Check the vendor advisory for the affected versions of arduino-esp32.
Severity: Critical (CVSS 9.8/10). Successful exploitation can lead to full system takeover.
Update to 3.3.8.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'arduino-esp32' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
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1Identify exposure identify
grep -r 'arduino-esp32' . | 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
arduino-esp32を grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade arduino-esp32 to 3.3.8ステージング環境で 3.3.8 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
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3Post-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。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
References
- exploit github.com