CVE-2026-124959 (GCVE-0-2026-124959)

Vulnerability from cvelistv5 – Published: 2026-11-09 15:04 – Updated: 2026-11-09 15:04
VLAI
Title
Nmaslib Hnswlib and Spotify Voyager HNSW Index Deserialization Heap Out-of-Bounds Write
Summary
The loadIndex function in nmslib hnswlib and Spotify Voyager does not verify that the element count in a serialized HNSW index is within the stored capacity used to allocate the heap buffer. An attacker can supply a crafted index file with an element count greater than the stored capacity, causing the loader to write beyond the allocated buffer and potentially crash the application when it loads the file.
Severity
No CVSS data available.
CWE
Assigner
certcc CNA
References
Impacted products
Vendor Product Version
Spotify Voyager Affected: 2.0.7 , ≤ 2.1.1 (custom)
Create a notification for this product.
hnswlib hnswlib Affected: 0.5.0 , ≤ 0.9.0 (custom)
Create a notification for this product.
Show details on NVD website
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "product": "Voyager",
          "vendor": "Spotify",
          "versions": [
            {
              "lessThanOrEqual": "2.1.1",
              "status": "affected",
              "version": "2.0.7",
              "versionType": "custom"
            }
          ]
        },
        {
          "product": "hnswlib",
          "vendor": "hnswlib",
          "versions": [
            {
              "lessThanOrEqual": "0.9.0",
              "status": "affected",
              "version": "0.5.0",
              "versionType": "custom"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "The loadIndex function in nmslib hnswlib and Spotify Voyager does not verify that the element count in a serialized HNSW index is within the stored capacity used to allocate the heap buffer. An attacker can supply a crafted index file with an element count greater than the stored capacity, causing the loader to write beyond the allocated buffer and potentially crash the application when it loads the file."
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "description": "CWE-787 Out-of-bounds Write",
              "lang": "en"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-11-09T15:04:38.649Z",
        "orgId": "37e5125f-f79b-445b-8fad-9564f167944b",
        "shortName": "certcc"
      },
      "references": [
        {
          "url": "https://m00dy.sh/notes/when-an-hnsw-index-lies-about-its-capacity"
        },
        {
          "url": "https://github.com/nmslib/hnswlib"
        },
        {
          "url": "https://github.com/spotify/voyager"
        }
      ],
      "source": {
        "discovery": "UNKNOWN"
      },
      "title": "Nmaslib Hnswlib and Spotify Voyager HNSW Index Deserialization Heap Out-of-Bounds Write",
      "x_generator": {
        "engine": "VINCE 4.0.2",
        "env": "prod",
        "origin": "https://cveawg.mitre.org/api/cve/CVE-2026-124959"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "37e5125f-f79b-445b-8fad-9564f167944b",
    "assignerShortName": "certcc",
    "cveId": "CVE-2026-124959",
    "datePublished": "2026-11-09T15:04:38.649Z",
    "dateReserved": "2026-11-09T15:02:37.082Z",
    "dateUpdated": "2026-11-09T15:04:38.649Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}



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