{"id":"CVE-2026-14986","aliases":["EUVD-2026-78204","GHSA-jmjj-w736-fw2j"],"status":"published","title":"Out-of-bounds write in it51xxx I2C target FIFO ISR on oversized write transaction","description":"The ITE it51xxx I2C driver, when operating as an I2C target (slave) in buffer mode (CONFIG_I2C_TARGET + CONFIG_I2C_TARGET_BUFFER_MODE), copies host-supplied write data into the fixed-size data-\u003etarget_in_buffer inside its target FIFO interrupt handler target_i2c_isr_fifo() in drivers/i2c/i2c_ite_it51xxx.c. The copy loop stores to target_in_buffer[i + data-\u003ew_index] and only checks data-\u003ew_index against sizeof(data-\u003etarget_in_buffer) after the write has already completed, so the bounds check cannot prevent the overflow.\n\nThe running index data-\u003ew_index accumulates count bytes on every FIFO-fill interrupt of an ongoing transaction and is reset to zero only on a STOP or timeout condition. An I2C host that streams a single write transaction longer than the buffer (default CONFIG_I2C_TARGET_IT51XXX_MAX_BUF_SIZE = 256 bytes) drives data-\u003ew_index past the end of the buffer, and each subsequent host byte is written out of bounds into the adjacent data-\u003etarget_out_buffer and following static device data.\n\nThe trigger is a malicious or misbehaving I2C master on the same bus (for example a compromised application processor or a rogue device on an exposed I2C bus); no software privilege on the victim is required and the handler runs in the target's kernel/firmware context. Because both the written values and the overflow length are attacker-controlled, this is an out-of-bounds write that can crash the controller or be shaped toward code execution. The fix adds a pre-write bounds check in target_i2c_fifo_read_to_buf() that aborts and resets the FIFO before any out-of-bounds store.","severity":{"version":"3.1","score":6.8,"vector":"CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-11","score":0.00278,"percentile":0.20456,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-787"],"published":"2026-09-14T22:07:46Z","modified":"2026-11-11T02:47:55Z","products":[{"vendor":"zephyrproject","product":"zephyr"},{"vendor":"zephyrproject-rtos","product":"zephyr"}],"references":[{"url":"https://github.com/zephyrproject-rtos/zephyr/commit/eac92173cf13bba4e6c6eea3460ee6085513d86d","tags":["patch","fix"]},{"url":"https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-jmjj-w736-fw2j","tags":["advisory"]},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/14xxx/CVE-2026-14986.json","tags":["advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-14986","tags":["advisory"]},{"url":"https://github.com/zephyrproject-rtos/zephyr","tags":["package"]}],"sources":{"cve":[{"id":"CVE-2026-14986","title":"Out-of-bounds write in it51xxx I2C target FIFO ISR on oversized write transaction","description":"The ITE it51xxx I2C driver, when operating as an I2C target (slave) in buffer mode (CONFIG_I2C_TARGET + CONFIG_I2C_TARGET_BUFFER_MODE), copies host-supplied write data into the fixed-size data-\u003etarget_in_buffer inside its target FIFO interrupt handler target_i2c_isr_fifo() in drivers/i2c/i2c_ite_it51xxx.c. The copy loop stores to target_in_buffer[i + data-\u003ew_index] and only checks data-\u003ew_index against sizeof(data-\u003etarget_in_buffer) after the write has already completed, so the bounds check cannot prevent the overflow.\n\nThe running index data-\u003ew_index accumulates count bytes on every FIFO-fill interrupt of an ongoing transaction and is reset to zero only on a STOP or timeout condition. An I2C host that streams a single write transaction longer than the buffer (default CONFIG_I2C_TARGET_IT51XXX_MAX_BUF_SIZE = 256 bytes) drives data-\u003ew_index past the end of the buffer, and each subsequent host byte is written out of bounds into the adjacent data-\u003etarget_out_buffer and following static device data.\n\nThe trigger is a malicious or misbehaving I2C master on the same bus (for example a compromised application processor or a rogue device on an exposed I2C bus); no software privilege on the victim is required and the handler runs in the target's kernel/firmware context. Because both the written values and the overflow length are attacker-controlled, this is an out-of-bounds write that can crash the controller or be shaped toward code execution. The fix adds a pre-write bounds check in target_i2c_fifo_read_to_buf() that aborts and resets the FIFO before any out-of-bounds store.","status":"published","published":"2026-09-14T22:07:46.392Z","modified":"2026-09-15T13:43:00.316Z","cvss":[{"version":"3.1","score":6.8,"vector":"CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"medium","assessor":"cna"}],"cwes":["CWE-787"],"updated_at":"2026-11-02T13:38:32.13011Z"}],"euvd":[{"id":"EUVD-2026-78204","description":"The ITE it51xxx I2C driver, when operating as an I2C target (slave) in buffer mode (CONFIG_I2C_TARGET + CONFIG_I2C_TARGET_BUFFER_MODE), copies host-supplied write data into the fixed-size data-\u003etarget_in_buffer inside its target FIFO interrupt handler target_i2c_isr_fifo() in drivers/i2c/i2c_ite_it51xxx.c. The copy loop stores to target_in_buffer[i + data-\u003ew_index] and only checks data-\u003ew_index against sizeof(data-\u003etarget_in_buffer) after the write has already completed, so the bounds check cannot prevent the overflow.\n\nThe running index data-\u003ew_index accumulates count bytes on every FIFO-fill interrupt of an ongoing transaction and is reset to zero only on a STOP or timeout condition. An I2C host that streams a single write transaction longer than the buffer (default CONFIG_I2C_TARGET_IT51XXX_MAX_BUF_SIZE = 256 bytes) drives data-\u003ew_index past the end of the buffer, and each subsequent host byte is written out of bounds into the adjacent data-\u003etarget_out_buffer and following static device data.\n\nThe trigger is a malicious or misbehaving I2C master on the same bus (for example a compromised application processor or a rogue device on an exposed I2C bus); no software privilege on the victim is required and the handler runs in the target's kernel/firmware context. Because both the written values and the overflow length are attacker-controlled, this is an out-of-bounds write that can crash the controller or be shaped toward code execution. The fix adds a pre-write bounds check in target_i2c_fifo_read_to_buf() that aborts and resets the FIFO before any out-of-bounds store.","status":"published","published":"2026-09-14T22:07:46Z","modified":"2026-09-15T13:43:00Z","cvss":[{"version":"3.1","score":6.8,"vector":"CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"medium"}],"updated_at":"2026-11-02T17:28:18.438671Z"}],"nvd":[{"id":"CVE-2026-14986","description":"The ITE it51xxx I2C driver, when operating as an I2C target (slave) in buffer mode (CONFIG_I2C_TARGET + CONFIG_I2C_TARGET_BUFFER_MODE), copies host-supplied write data into the fixed-size data-\u003etarget_in_buffer inside its target FIFO interrupt handler target_i2c_isr_fifo() in drivers/i2c/i2c_ite_it51xxx.c. The copy loop stores to target_in_buffer[i + data-\u003ew_index] and only checks data-\u003ew_index against sizeof(data-\u003etarget_in_buffer) after the write has already completed, so the bounds check cannot prevent the overflow.\n\nThe running index data-\u003ew_index accumulates count bytes on every FIFO-fill interrupt of an ongoing transaction and is reset to zero only on a STOP or timeout condition. An I2C host that streams a single write transaction longer than the buffer (default CONFIG_I2C_TARGET_IT51XXX_MAX_BUF_SIZE = 256 bytes) drives data-\u003ew_index past the end of the buffer, and each subsequent host byte is written out of bounds into the adjacent data-\u003etarget_out_buffer and following static device data.\n\nThe trigger is a malicious or misbehaving I2C master on the same bus (for example a compromised application processor or a rogue device on an exposed I2C bus); no software privilege on the victim is required and the handler runs in the target's kernel/firmware context. Because both the written values and the overflow length are attacker-controlled, this is an out-of-bounds write that can crash the controller or be shaped toward code execution. The fix adds a pre-write bounds check in target_i2c_fifo_read_to_buf() that aborts and resets the FIFO before any out-of-bounds store.","status":"published","published":"2026-09-14T23:17:15.533Z","modified":"2026-09-18T19:11:57.76Z","cvss":[{"version":"3.1","score":6.8,"vector":"CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"medium","assessor":"secondary"}],"cwes":["CWE-787"],"updated_at":"2026-11-02T14:12:47.335523Z"}],"osv":[{"id":"CVE-2026-14986","title":"Out-of-bounds write in it51xxx I2C target FIFO ISR on oversized write transaction","description":"The ITE it51xxx I2C driver, when operating as an I2C target (slave) in buffer mode (CONFIG_I2C_TARGET + CONFIG_I2C_TARGET_BUFFER_MODE), copies host-supplied write data into the fixed-size data-\u003etarget_in_buffer inside its target FIFO interrupt handler target_i2c_isr_fifo() in drivers/i2c/i2c_ite_it51xxx.c. The copy loop stores to target_in_buffer[i + data-\u003ew_index] and only checks data-\u003ew_index against sizeof(data-\u003etarget_in_buffer) after the write has already completed, so the bounds check cannot prevent the overflow.\n\nThe running index data-\u003ew_index accumulates count bytes on every FIFO-fill interrupt of an ongoing transaction and is reset to zero only on a STOP or timeout condition. An I2C host that streams a single write transaction longer than the buffer (default CONFIG_I2C_TARGET_IT51XXX_MAX_BUF_SIZE = 256 bytes) drives data-\u003ew_index past the end of the buffer, and each subsequent host byte is written out of bounds into the adjacent data-\u003etarget_out_buffer and following static device data.\n\nThe trigger is a malicious or misbehaving I2C master on the same bus (for example a compromised application processor or a rogue device on an exposed I2C bus); no software privilege on the victim is required and the handler runs in the target's kernel/firmware context. Because both the written values and the overflow length are attacker-controlled, this is an out-of-bounds write that can crash the controller or be shaped toward code execution. The fix adds a pre-write bounds check in target_i2c_fifo_read_to_buf() that aborts and resets the FIFO before any out-of-bounds store.","status":"published","published":"2026-09-14T22:07:46.392Z","modified":"2026-11-11T10:47:27.049539247Z","cvss":[{"version":"3.1","score":6.8,"vector":"CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"medium"}],"cwes":["CWE-787"],"updated_at":"2026-11-11T03:22:28.447808Z"}]}}