FKIE_CVE-2026-40279

Vulnerability from fkie_nvd - Published: 2026-04-21 17:16 - Updated: 2026-04-27 19:49
Severity ?
3.7 (Low) - CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L
Summary
BACnet Stack is a BACnet open source protocol stack C library for embedded systems. Prior to 1.4.3, decode_signed32() in src/bacnet/bacint.c reconstructs a 32-bit signed integer from four APDU bytes using signed left shifts. When any of the four bytes has bit 7 set (value ≥ 0x80), the left-shift operation overflows a signed int32_t, which is undefined behavior per the C standard. This is flagged thousands of times per minute by UndefinedBehaviorSanitizer on any BACnet input containing signed-integer property values with high-bit-set bytes. This vulnerability is fixed in 1.4.3.
References
security-advisories@github.comhttps://github.com/bacnet-stack/bacnet-stack/security/advisories/GHSA-326g-j95f-gmxvExploit, Mitigation, Vendor Advisory
134c704f-9b21-4f2e-91b3-4a467353bcc0https://github.com/bacnet-stack/bacnet-stack/security/advisories/GHSA-326g-j95f-gmxvExploit, Mitigation, Vendor Advisory
Impacted products
Vendor Product Version
bacnetstack bacnet_stack *
To clipboard 

{
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:bacnetstack:bacnet_stack:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "B46C7C2C-2BC3-4A72-AEDC-746D4D76A2DE",
              "versionEndExcluding": "1.4.3",
              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "BACnet Stack is a BACnet open source protocol stack C library for embedded systems. Prior to 1.4.3, decode_signed32() in src/bacnet/bacint.c reconstructs a 32-bit signed integer from four APDU bytes using signed left shifts. When any of the four bytes has bit 7 set (value \u2265 0x80), the left-shift operation overflows a signed int32_t, which is undefined behavior per the C standard. This is flagged thousands of times per minute by UndefinedBehaviorSanitizer on any BACnet input containing signed-integer property values with high-bit-set bytes. This vulnerability is fixed in 1.4.3."
    }
  ],
  "id": "CVE-2026-40279",
  "lastModified": "2026-04-27T19:49:23.133",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "HIGH",
          "attackVector": "NETWORK",
          "availabilityImpact": "LOW",
          "baseScore": 3.7,
          "baseSeverity": "LOW",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L",
          "version": "3.1"
        },
        "exploitabilityScore": 2.2,
        "impactScore": 1.4,
        "source": "security-advisories@github.com",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-04-21T17:16:54.853",
  "references": [
    {
      "source": "security-advisories@github.com",
      "tags": [
        "Exploit",
        "Mitigation",
        "Vendor Advisory"
      ],
      "url": "https://github.com/bacnet-stack/bacnet-stack/security/advisories/GHSA-326g-j95f-gmxv"
    },
    {
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
      "tags": [
        "Exploit",
        "Mitigation",
        "Vendor Advisory"
      ],
      "url": "https://github.com/bacnet-stack/bacnet-stack/security/advisories/GHSA-326g-j95f-gmxv"
    }
  ],
  "sourceIdentifier": "security-advisories@github.com",
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-758"
        }
      ],
      "source": "security-advisories@github.com",
      "type": "Secondary"
    }
  ]
}


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