libsmi through 0.5.0 Out-of-Bounds Write via smiValueAsString OCTET STRING DEFVAL

{
  "id": "c9de5035823c95f141552a58543d24a756940f28c2865cca3a6b2c1ea53d613b",
  "url": "https://osv.dev/vulnerability/CVE-2026-111137",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "libsmi through 0.5.0 Out-of-Bounds Write via smiValueAsString OCTET STRING DEFVAL",
    "summary": "libsmi through 0.5.0 contains an out-of-bounds write vulnerability in smiValueAsString() in lib/smi.c that allows attackers to overflow a fixed 1024-byte static buffer through hex rendering of OCTET STRING values. Attackers can supply a crafted MIB with an OCTET STRING DEFVAL of 512 or more octets and a leading 0x00 byte to corrupt adjacent library globals and crash smidump or other consumers.",
    "evidence": "osv:CVE-2026-111137",
    "products": [],
    "severity": "medium",
    "structured": {
      "id": "CVE-2026-111137",
      "aliases": [
        "CVE-2026-111137"
      ],
      "metrics": [
        {
          "type": "CVSS_V4",
          "score": "CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:H/SC:N/SI:N/SA:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/amartin755/libsmi",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "last_affected": "c58307210fe995ec419db976eb234aebc71a9216"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "last_affected": "0.5.0"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StandardRange"
                  },
                  {
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "last_affected": "0.5.0"
                      }
                    ],
                    "source": "DESCRIPTION"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v0.5.0",
            "v0.4.8"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-111137.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:27.634215579Z",
      "provider": "osv",
      "references": [
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/111xxx/CVE-2026-111137.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-111137",
        "https://www.vulncheck.com/advisories/libsmi-through-0.5.0-out-of-bounds-write-via-smivalueasstring-octet-string-defval",
        "https://github.com/amartin755/libsmi",
        "https://github.com/amartin755/libsmi/blob/c58307210fe995ec419db976eb234aebc71a9216/lib/smi.c#L479-L566",
        "https://hackmd.io/@haind-pwn/libsmi-smivalueasstring-octetstring-defval-oob-write"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-787"
        ],
        "cna_assigner": "VulnCheck",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/111xxx/CVE-2026-111137.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-111137",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 494412,
  "published_at": "2026-10-15T18:57:30.581+00:00"
}