FKIE_CVE-2026-48691

Vulnerability from fkie_nvd - Published: 2026-05-26 17:16 - Updated: 2026-05-27 21:16
Severity
9.8 (Critical) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
7.3 (High) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
Summary
FastNetMon Community Edition through 1.2.9 contains an integer overflow in the BGP AS_PATH attribute encoder. In src/bgp_protocol.hpp, the IPv4UnicastAnnounce::get_attributes() function computes attribute_length as 'sizeof(bgp_as_path_segment_element_t) + this->as_path_asns.size() * sizeof(uint32_t)' and stores it in a uint8_t field (line 600-605). Since uint8_t can only hold values 0-255, an AS_PATH containing more than 63 ASNs (2 + 64*4 = 258 > 255) causes silent truncation. The truncated length is used for buffer sizing, while the actual data written is the full untruncated amount, resulting in a heap buffer overflow. Similarly, the path_segment_length field at line 621 is also uint8_t, truncating with more than 255 ASNs.
References
cve@mitre.orghttps://github.com/pavel-odintsov/fastnetmonProduct
cve@mitre.orghttps://github.com/pavel-odintsov/fastnetmon/blob/master/src/bgp_protocol.hppProduct
cve@mitre.orghttps://lorikeetsecurity.com/blog/fastnetmon-cve-2026-48691-bgp-as-path-overflowThird Party Advisory
Impacted products
Vendor Product Version
pavel-odintsov fastnetmon *
To clipboard 

{
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:pavel-odintsov:fastnetmon:*:*:*:*:community:*:*:*",
              "matchCriteriaId": "E712A01F-3AD7-4CC2-9A8B-F8C63756EBBF",
              "versionEndIncluding": "1.2.9",
              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "FastNetMon Community Edition through 1.2.9 contains an integer overflow in the BGP AS_PATH attribute encoder. In src/bgp_protocol.hpp, the IPv4UnicastAnnounce::get_attributes() function computes attribute_length as \u0027sizeof(bgp_as_path_segment_element_t) + this-\u003eas_path_asns.size() * sizeof(uint32_t)\u0027 and stores it in a uint8_t field (line 600-605). Since uint8_t can only hold values 0-255, an AS_PATH containing more than 63 ASNs (2 + 64*4 = 258 \u003e 255) causes silent truncation. The truncated length is used for buffer sizing, while the actual data written is the full untruncated amount, resulting in a heap buffer overflow. Similarly, the path_segment_length field at line 621 is also uint8_t, truncating with more than 255 ASNs."
    }
  ],
  "id": "CVE-2026-48691",
  "lastModified": "2026-05-27T21:16:19.090",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 9.8,
          "baseSeverity": "CRITICAL",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 5.9,
        "source": "nvd@nist.gov",
        "type": "Primary"
      },
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "LOW",
          "baseScore": 7.3,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "LOW",
          "integrityImpact": "LOW",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L",
          "version": "3.1"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 3.4,
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-05-26T17:16:53.670",
  "references": [
    {
      "source": "cve@mitre.org",
      "tags": [
        "Product"
      ],
      "url": "https://github.com/pavel-odintsov/fastnetmon"
    },
    {
      "source": "cve@mitre.org",
      "tags": [
        "Product"
      ],
      "url": "https://github.com/pavel-odintsov/fastnetmon/blob/master/src/bgp_protocol.hpp"
    },
    {
      "source": "cve@mitre.org",
      "tags": [
        "Third Party Advisory"
      ],
      "url": "https://lorikeetsecurity.com/blog/fastnetmon-cve-2026-48691-bgp-as-path-overflow"
    }
  ],
  "sourceIdentifier": "cve@mitre.org",
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-190"
        }
      ],
      "source": "nvd@nist.gov",
      "type": "Primary"
    },
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-122"
        },
        {
          "lang": "en",
          "value": "CWE-190"
        }
      ],
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
      "type": "Secondary"
    }
  ]
}


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