FKIE_CVE-2026-107836

Vulnerability from fkie_nvd - Published: 2026-10-09 18:17 - Updated: 2026-10-09 18:17
Severity
7.1 (High) - CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:N/VA:H/SC:N/SI:N/SA:N
Summary
RIOT is an open-source microcontroller operating system designed for Internet of Things devices and other embedded systems. In 2026.07 and earlier, the nanoCoAP client function nanocoap_sock_get_slice() in sys/net/application_layer/nanocoap/sock.c accepts a Block2 response when _block_cb() sees the expected block number without also 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 the derived offset to exceed the client slice offset and making ctx->offset - offset underflow in _2buf_slice(). The resulting buffer-relative calculation can read before the payload buffer and crash the client, causing denial of service and potentially exposing adjacent memory. No fixed release is available as of this review.
References
security-advisories@github.comhttps://github.com/RIOT-OS/RIOT/commit/49b894cbe091510093273b98d92c4a17167d6839
security-advisories@github.comhttps://github.com/RIOT-OS/RIOT/pull/22518
security-advisories@github.comhttps://github.com/RIOT-OS/RIOT/security/advisories/GHSA-x924-p5fq-26pc
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "product": "RIOT",
          "vendor": "RIOT-OS",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c= 2026.07"
            }
          ]
        }
      ],
      "source": "security-advisories@github.com"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "RIOT is an open-source microcontroller operating system designed for Internet of Things devices and other embedded systems. In 2026.07 and earlier, the nanoCoAP client function nanocoap_sock_get_slice() in sys/net/application_layer/nanocoap/sock.c accepts a Block2 response when _block_cb() sees the expected block number without also 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 the derived offset to exceed the client slice offset and making ctx-\u003eoffset - offset underflow in _2buf_slice(). The resulting buffer-relative calculation can read before the payload buffer and crash the client, causing denial of service and potentially exposing adjacent memory. No fixed release is available as of this review."
    }
  ],
  "id": "CVE-2026-107836",
  "lastModified": "2026-10-09T18:17:05.310",
  "metrics": {
    "cvssMetricV40": [
      {
        "cvssData": {
          "Automatable": "NOT_DEFINED",
          "Recovery": "NOT_DEFINED",
          "Safety": "NOT_DEFINED",
          "attackComplexity": "LOW",
          "attackRequirements": "NONE",
          "attackVector": "NETWORK",
          "availabilityRequirement": "NOT_DEFINED",
          "baseScore": 7.1,
          "baseSeverity": "HIGH",
          "confidentialityRequirement": "NOT_DEFINED",
          "exploitMaturity": "NOT_DEFINED",
          "integrityRequirement": "NOT_DEFINED",
          "modifiedAttackComplexity": "NOT_DEFINED",
          "modifiedAttackRequirements": "NOT_DEFINED",
          "modifiedAttackVector": "NOT_DEFINED",
          "modifiedPrivilegesRequired": "NOT_DEFINED",
          "modifiedSubAvailabilityImpact": "NOT_DEFINED",
          "modifiedSubConfidentialityImpact": "NOT_DEFINED",
          "modifiedSubIntegrityImpact": "NOT_DEFINED",
          "modifiedUserInteraction": "NOT_DEFINED",
          "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
          "modifiedVulnConfidentialityImpact": "NOT_DEFINED",
          "modifiedVulnIntegrityImpact": "NOT_DEFINED",
          "privilegesRequired": "NONE",
          "providerUrgency": "NOT_DEFINED",
          "subAvailabilityImpact": "NONE",
          "subConfidentialityImpact": "NONE",
          "subIntegrityImpact": "NONE",
          "userInteraction": "PASSIVE",
          "valueDensity": "NOT_DEFINED",
          "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
          "version": "4.0",
          "vulnAvailabilityImpact": "HIGH",
          "vulnConfidentialityImpact": "LOW",
          "vulnIntegrityImpact": "NONE",
          "vulnerabilityResponseEffort": "NOT_DEFINED"
        },
        "source": "security-advisories@github.com",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-107836",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-10-09T17:59:40.461358Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-10-09T18:17:05.310",
  "references": [
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/RIOT-OS/RIOT/commit/49b894cbe091510093273b98d92c4a17167d6839"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/RIOT-OS/RIOT/pull/22518"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/RIOT-OS/RIOT/security/advisories/GHSA-x924-p5fq-26pc"
    }
  ],
  "sourceIdentifier": "security-advisories@github.com",
  "vulnStatus": "Received",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-125"
        },
        {
          "lang": "en",
          "value": "CWE-191"
        }
      ],
      "source": "security-advisories@github.com",
      "type": "Primary"
    }
  ]
}



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