CVE-2026-107838 (GCVE-0-2026-107838)
Vulnerability from cvelistv5 – Published: 2026-10-09 17:55 – Updated: 2026-10-13 17:07
VLAI
EPSS
VEX
Title
RIOT: nanocoap_fileserver ignores response initialization failure, leading to reachable assertion
Summary
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.
Severity
7.5 (High)
SSVC
Exploitation: none
Automatable: yes
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-10-13 17:07 UTC
Assigner
References
3 references
| URL | Tags |
|---|---|
| https://github.com/RIOT-OS/RIOT/security/advisori… | x_refsource_CONFIRM |
| https://github.com/RIOT-OS/RIOT/pull/22745 | x_refsource_MISC |
| https://github.com/RIOT-OS/RIOT/commit/d3a47289c5… | x_refsource_MISC |
Impacted products
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Sightings
| Author | Source | Type | Date | Other |
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Nomenclature
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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