1/3 Bug Advisory Title ESP32-C61 Series Chips Bug Advisory Issue Date 2026/01/08 Advisory Number AR2025-009 Serial Number NA Version V1.0 Issue Summary The following issues have been identified in the ESP32-C61 series chips: Issue 1: Bluetooth LE Connection Drop When ESP32-C61 chips (chip revision v1.0 and later) run ESP-IDF v5.5.1 and pair with mobile phones or other Bluetooth LE devices over encrypted connections, a MIC (Message Integrity Check) error may occur, causing the connection to drop unexpectedly (error code 0x3d). Issue 2: PSRAM Reset Hang When ESP32-C61 series chips run ESP-IDF v5.5.1 with PSRAM enabled, CPU or digital reset operations may hang. This triggers a secondary RTC WDT reset. If the rollback feature (CONFIG_BOOTLOADER_APP_ROLLBACK_ENABLE, disabled by default) is enabled, this sequence may result in an OTA rollback. Issue 3: AES and SHA Access to PSRAM When ESP32-C61 chips run ESP-IDF v5.5.1, PSRAM data may be corrupted when AES or SHA hardware accesses buffers that are not aligned to a 16-byte boundary. Issue 4: Wi-Fi and BLE Coexistence Stability When ESP32-C61 series chips run ESP-IDF v5.5.1, Brown-out Reset may occur frequently during Wi-Fi/BLE coexistence stress testing. Impact Analysis Affected Product Series: 2/3 These issues affect the ESP32-C61 series of chips. ESP-IDF Affected Versions: Issue 1: Bluetooth LE Connection Drop ESP-IDF Branch Affected Commit IDs Affected ESP-IDF Versions master Commits before c705b71 (excluded) No official release yet release/v6.0 Commits before b65d10f (excluded) No official release yet release/v5.5 Commits before 443bbf5 (excluded) v5.5.1 Issue 2: PSRAM Reset Hang ESP-IDF Branch Affected Commit IDs Affected ESP-IDF Versions master Commits before c467c91 (excluded) No official release yet release/v6.0 Commits before 3df1ee1 (excluded) v6.0-beta1 release/v5.5 Commits before ddb9f5d (excluded) v5.5.1 Issue 3: AES and SHA Access to PSRAM ESP-IDF Branch Affected Commit IDs Affected ESP-IDF Versions master Commits before da1ff70 (excluded) No official release yet release/v6.0 Commits before 145de94 (excluded) v6.0-beta1 release/v5.5 Commits before 86bd3d3 (excluded) v5.5.1 Issue 4: Wi-Fi and BLE Coexistence Stability ESP-IDF Branch Affected Commit IDs Affected ESP-IDF Versions master Commits before c61b0be (excluded) No official release yet release/v6.0 Commits before 7e87423 (excluded) v6.0-beta1 release/v5.5 Commits before b1e3248 (excluded) 5.5.1 Note: ESP32-C61 is supported starting from ESP-IDF v5.5.1. Mitigation 3/3 ESP-IDF Patched Versions: Issue 1: Bluetooth LE Connection Drop ESP-IDF Branch Fixed Commit IDs Fixed ESP-IDF Versions master c705b71 v6.0 release/v6.0 b65d10f v6.0 release/v5.5 443bbf5 v5.5.2 Issue 2: PSRAM Reset Hang ESP-IDF Branch Fixed Commit IDs Fixed ESP-IDF Versions master c467c91 v6.1 release/v6.0 3df1ee1 v6.0 release/v5.5 ddb9f5d v5.5.2 Issue 3: AES and SHA Access to PSRAM ESP-IDF Branch Fixed Commit IDs Fixed ESP-IDF Versions master da1ff70 v6.1 release/v6.0 145de94 v6.0 release/v5.5 86bd3d3 v5.5.2 Issue 4: Wi-Fi and BLE Coexistence Stability ESP-IDF Branch Fixed Commit IDs Fixed ESP-IDF Versions master c61b0be v6.1 release/v6.0 7e87423 v6.0 release/v5.5 b1e3248 v5.5.2 Recommendations for Application Developers If your application is affected by the issues described above, and you are using an affected ESP-IDF version, it is recommended to upgrade ESP-IDF to the patched ESP-IDF version (see the table above). If you encounter any issues during the upgrade process, please provide Espressif with the ESP-IDF version number or Commit ID. We will confirm and handle related matters as soon as possible.