Executive brief
A vulnerability exists in the software framework used by Espressif IoT devices (such as ESP32) when they act as a Wi-Fi hotspot or DHCP server. An attacker connected to the same local network can send a specially crafted request that causes the device to crash or stop assigning IP addresses to other users. This results in a denial of service, preventing other devices from connecting to the network, though it does not appear to expose private data.
Technical details
An out-of-bounds read vulnerability exists in the DHCP server option parser (`parse_options()` in `components/lwip/apps/dhcpserver/dhcpserver.c`) of the Espressif IoT Development Framework (ESP-IDF). The parser fails to validate that the length byte and declared payload length of BOOTP/DHCP options remain within the bounds of the received packet buffer. An unauthenticated attacker on the same Layer-2 network can exploit this by sending a malformed DHCP broadcast. While the read data is not leaked to the attacker, the flaw can cause the lwIP/DHCP server task to crash or corrupt the parser state, resulting in a denial of service for all clients. The issue has been patched in versions 5.2.8, 5.3.6, 5.4.5, 5.5.5, and 6.0.2.
Affected products
- Espressif Systems ESP-IDF 5.2.7, 5.3.5, 5.4.4, 5.5.4, 6.0.1
Timeline
- 2026-05-21: advisory: GitHub advisory published by Espressif
- 2026-06-10: disclosed: CVE published to NVD
References
- https://github.com/espressif/esp-idf/commit/2bf4dd12002dbae60a4b21abff010ecb2b8ee82b
- https://github.com/espressif/esp-idf/commit/2da2db43fd7e0bcff9e7b95f54f388296bb6f911
- https://github.com/espressif/esp-idf/commit/8b4b5d5301815198d177974ffc24848f47748248
- https://github.com/espressif/esp-idf/commit/9f713dbc94982d917f2d12964b233cd9efa4aeba
- https://github.com/espressif/esp-idf/commit/d51b1076092487e533eadf8b48c9c8579d3a6712
- https://github.com/espressif/esp-idf/commit/fba5f995436a3e3139f768b6d8f1a74d5ce1d318
- https://github.com/espressif/esp-idf/security/advisories/GHSA-g764-gwc3-75m5