CVE-2026-107838
HighCVSS 7.5Summary
RIOT from version 2023.07 through 2026.07 ignores a failure returned by _resp_init() in nanocoap_fileserver when coap_build_reply() cannot fit a response header into the response buffer. A remote client can send a CoAP request with a large extended token, causing response initialization to fail and leading to an assertion that terminates the service or task.
Risk Assessment
The attack can cause service or task termination on an IoT device, potentially disrupting its operation.
Recommendation
No fixed release is available; monitor the repository and apply the patch when available.
Other vulnerabilities in RIOT
See all- CVE-2026-107837High
RIOT in 2026.07 and earlier, the _receive() function in gnrc_sixlowpan.c can route an undersized packet into SFF fragment handling after only a minimal payload check. A remote attacker can send a malformed 6LoWPAN fragment causing read beyond the packet buffer, potentially disclosing memory and crashing the network stack.
- CVE-2026-107836High
RIOT in 2026.07 and earlier, the nanocoap_sock_get_slice() function accepts a Block2 response when _block_cb() sees the expected block number without verifying that the server-controlled szx and derived offset match the requested block geometry. A malicious CoAP server can return the expected block number with a larger block size, causing offset underflow and read before the payload buffer, potentially crashing the client.
- CVE-2017-8289Critical
A stack-based buffer overflow in the ipv6_addr_from_str function in RIOT prior to April 25, 2017, can be exploited by local and potentially remote attackers. Attackers may cause a denial of service or possibly have unspecified other impacts via a malformed IPv6 address.
Original NVD description (English source)
RIOT is an open-source microcontroller operating system designed for Internet of Things devices and other embedded systems. From version 2023.07 through version 2026.07, nanocoap_fileserver callers in sys/net/application_layer/nanocoap/fileserver.c ignore a failure returned by _resp_init() when coap_build_reply() cannot fit a response header into the response buffer. A remote client can send a CoAP request with a sufficiently large extended token when nanocoap_token_ext is enabled, causing response initialization to fail while _get_file() or _get_directory() continues with stale response state. The path then reaches _calc_szx2() and its pdu->payload_len > reserve assertion, terminating the affected service or device task. No fixed release is available as of this review.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS