CVE-2026-27703
CVE-2026-27703 is a high-severity vulnerability in Riot-os Riot with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-787.
Key facts
- Severity: High (CVSS 3.x base score 7.5)
- EPSS exploit prediction: 0% (38th percentile)
- Actively exploited: Not listed in CISA KEV
- EU (EUVD) id: EUVD-2026-11305
- Weakness: CWE-787
- Affected product: Riot-os Riot
- Published:
- Last modified:
Description
RIOT is an open-source microcontroller operating system, designed to match the requirements of Internet of Things (IoT) devices and other embedded devices. In 2026.01 and earlier, the default handler for the well_known_core resource coap_well_known_core_default_handler writes user-provided option data and other data into a fixed size buffer without validating the buffer is large enough to contain the response. This vulnerability allows an attacker to corrupt neighboring stack location, including security-sensitive addresses like the return address, leading to denial of service or arbitrary code execution.
Frequently asked questions
- What is CVE-2026-27703?
- RIOT is an open-source microcontroller operating system, designed to match the requirements of Internet of Things (IoT) devices and other embedded devices. In 2026.01 and earlier, the default handler for the well_known_core resource coap_well_known_core_default_handler writes user-provided option data and other data into a fixed size buffer without validating the buffer is large enough to contain the response. This vulnerability allows an attacker to corrupt neighboring stack location, including security-sensitive addresses like the return address, leading to denial of service or arbitrary code execution.
- How severe is CVE-2026-27703?
- CVE-2026-27703 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability none.
- Is CVE-2026-27703 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (38th percentile), an estimate of the probability of exploitation in the next 30 days.
- What products are affected by CVE-2026-27703?
- CVE-2026-27703 affects Riot-os Riot. See the affected-products list for the exact vulnerable versions.
- How do I fix CVE-2026-27703?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
- Does CVE-2026-27703 have an EU (EUVD) identifier?
- Yes. CVE-2026-27703 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-11305.
- When was CVE-2026-27703 published?
- CVE-2026-27703 was published on 2026-03-11 and last updated on 2026-06-17.
References
Affected products (1)
- cpe:2.3:o:riot-os:riot:*:*:*:*:*:*:*:*
More vulnerabilities in Riot-os Riot
- CVE-2026-22214 — Critical (CVSS 9.8): RIOT OS versions up to and including 2026.01-devel-317 contain a stack-based buffer overflow vulnerability in the ethos…
- CVE-2026-22213 — Critical (CVSS 9.8): RIOT OS versions up to and including 2026.01-devel-317 contain a stack-based buffer overflow vulnerability in the…
- CVE-2025-66647 — Critical (CVSS 9.8): RIOT is an open-source microcontroller operating system, designed to match the requirements of Internet of Things (IoT)…
- CVE-2025-53888 — Critical (CVSS 9.8): RIOT-OS, an operating system that supports Internet of Things devices, has an ineffective size check implemented with…
- CVE-2024-32017 — Critical (CVSS 9.8): RIOT is a real-time multi-threading operating system that supports a range of devices that are typically 8-bit, 16-bit…
- CVE-2023-33975 — Critical (CVSS 9.8): RIOT-OS, an operating system for Internet of Things (IoT) devices, contains a network stack with the ability to process…
All CVEs affecting Riot-os Riot →
Other CWE-787 (Out-of-bounds Write) vulnerabilities
- CVE-2026-42369 — Critical (CVSS 10.0): GV-VMS V20 is a Video Monitoring Software used to gather the feeds of many surveillance cameras and manage other…
- CVE-2026-4746 — Critical (CVSS 10.0): Out-of-bounds Write vulnerability in timeplus-io proton (base/poco/Foundation/src modules). This vulnerability is…
- CVE-2025-43300 — Critical (CVSS 10.0): An out-of-bounds write issue was addressed with improved bounds checking. This issue is fixed in iOS 15.8.5 and iPadOS…
- CVE-2025-24201 — Critical (CVSS 10.0): An out-of-bounds write issue was addressed with improved checks to prevent unauthorized actions. This issue is fixed in…
- CVE-2024-42479 — Critical (CVSS 10.0): llama.cpp provides LLM inference in C/C++. The unsafe `data` pointer member in the `rpc_tensor` structure can cause…
- CVE-2024-39791 — Critical (CVSS 10.0): Stack-based buffer overflow vulnerabilities affecting Vonets industrial wifi bridge relays and wifi bridge…