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TI-2026-31061 Aliases CVE-2026-42854

arduino-esp32: Stack buffer overflow in WebServer multipart boundary parsing leads to remote crash potential RCE

Priority HIGH 82CWE-121Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
Code execution
Confidentiality · integrity · availability
High · High · High
Fix status
Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA. Impact type from CWE-121 and the CVSS impact.

Summary

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.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00571 47th percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by NVD
Fix Fixed arduino-esp32 (espressif): 3.3.8

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
Automatable
Yes
Technical impact
Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
espressifarduino-esp32before 3.3.83.3.8Patch availableCNA
  • arduino-esp32 Vendorespressif Affected before 3.3.8 Fixed in 3.3.8 Patch available CNA

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:espressif:arduino-esp32:*:-:*:*:*:*:*:*before 3.3.8Vulnerableespressif
  • cpe:2.3:a:espressif:arduino-esp32:*:-:*:*:*:*:*:* Versions before 3.3.8 Vulnerable ·espressif

Remediation

  • Fix · CNA arduino-esp32 (espressif) Fixed in 3.3.8

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-42854
  2. 2026-10-25 EPSS moved to the below the 50th percentile

References

Exploit 1

  • TI-2026-30028 Improper validation of NBNS name_len in arduino-esp32 NetBIOS leads to memory corruption CVSS 3.1HIGH 8.8
  • TI-2026-31062 arduino-esp32: Digest authentication URI mismatch bypass in WebServer allows cross-resource replay attack CVSS 3.1HIGH 7.5
  • TI-2019-09398 The EAP peer implementation in Espressif ESP-IDF 2.0.0 through 4.0.0 and… CVSS 3.0MEDIUM 6.5

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences