CVE-2026-39855

{
  "id": "CVE-2026-39855",
  "sourceIdentifier": "[email protected]",
  "published": "2026-04-09T17:16:29.140",
  "lastModified": "2026-10-26T22:10:00.163",
  "vulnStatus": "Analyzed",
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "osslsigncode is a tool that implements Authenticode signing and timestamping. Prior to 2.13, an integer underflow vulnerability exists in osslsigncode version 2.12 and earlier in the PE page-hash computation code (pe_page_hash_calc()). When page hash processing is performed on a PE file, the function subtracts hdrsize from pagesize without first validating that pagesize >= hdrsize. If a malicious PE file sets SizeOfHeaders (hdrsize) larger than SectionAlignment (pagesize), the subtraction underflows and produces a very large unsigned length. The code allocates a zero-filled buffer of pagesize bytes and then attempts to hash pagesize - hdrsize bytes from that buffer. After the underflow, this results in an out-of-bounds read from the heap and can crash the process. The vulnerability can be triggered while signing a malicious PE file with page hashing enabled (-ph), or while verifying a malicious signed PE file that already contains page hashes. Verification of an already signed file does not require the verifier to pass -ph. This vulnerability is fixed in 2.13."
    },
    {
      "lang": "es",
      "value": "osslsigncode es una herramienta que implementa la firma Authenticode y el sellado de tiempo. Antes de la versión 2.13, existe una vulnerabilidad de desbordamiento negativo de enteros en osslsigncode versión 2.12 y anteriores en el código de cálculo de hash de página PE (pe_page_hash_calc()). Cuando se realiza el procesamiento de hash de página en un archivo PE, la función resta hdrsize de pagesize sin validar primero que pagesize >= hdrsize. Si un archivo PE malicioso establece SizeOfHeaders (hdrsize) mayor que SectionAlignment (pagesize), la resta sufre un desbordamiento negativo y produce una longitud sin signo muy grande. El código asigna un búfer rellenado con ceros de pagesize bytes y luego intenta aplicar hash a pagesize - hdrsize bytes de ese búfer. Después del desbordamiento negativo, esto resulta en una lectura fuera de límites de la pila y puede bloquear el proceso. La vulnerabilidad puede ser activada mientras se firma un archivo PE malicioso con el hash de página habilitado (-ph), o mientras se verifica un archivo PE firmado malicioso que ya contiene hashes de página. La verificación de un archivo ya firmado no requiere que el verificador pase -ph. Esta vulnerabilidad está corregida en la versión 2.13."
    }
  ],
  "affected": [
    {
      "source": "[email protected]",
      "affectedData": [
        {
          "vendor": "mtrojnar",
          "product": "osslsigncode",
          "versions": [
            {
              "version": "< 2.13",
              "status": "affected"
            }
          ]
        }
      ]
    }
  ],
  "metrics": {
    "cvssMetricV31": [
      {
        "source": "[email protected]",
        "type": "Secondary",
        "cvssData": {
          "version": "3.1",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H",
          "baseScore": 5.5,
          "baseSeverity": "MEDIUM",
          "attackVector": "LOCAL",
          "attackComplexity": "LOW",
          "privilegesRequired": "NONE",
          "userInteraction": "REQUIRED",
          "scope": "UNCHANGED",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "availabilityImpact": "HIGH"
        },
        "exploitabilityScore": 1.8,
        "impactScore": 3.6
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "timestamp": "2026-04-09T19:12:57.585841Z",
          "id": "CVE-2026-39855",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "version": "2.0.3"
        }
      }
    ]
  },
  "weaknesses": [
    {
      "source": "[email protected]",
      "type": "Secondary",
      "description": [
        {
          "lang": "en",
          "value": "CWE-125"
        },
        {
          "lang": "en",
          "value": "CWE-190"
        },
        {
          "lang": "en",
          "value": "CWE-191"
        }
      ]
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "operator": "OR",
          "negate": false,
          "cpeMatch": [
            {
              "vulnerable": true,
              "criteria": "cpe:2.3:a:osslsigncode_project:osslsigncode:*:*:*:*:*:*:*:*",
              "versionEndExcluding": "2.13",
              "matchCriteriaId": "3F16716F-B2C3-41F9-B32B-CFD011129F12"
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  "references": [
    {
      "url": "https://github.com/mtrojnar/osslsigncode/commit/2a5409b7c4b6c6fad2b093531e8fea6cf08e1568",
      "source": "[email protected]",
      "tags": [
        "Patch"
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    },
    {
      "url": "https://github.com/mtrojnar/osslsigncode/releases/tag/2.13",
      "source": "[email protected]",
      "tags": [
        "Product",
        "Release Notes"
      ]
    },
    {
      "url": "https://github.com/mtrojnar/osslsigncode/security/advisories/GHSA-76vv-x5rr-q3mr",
      "source": "[email protected]",
      "tags": [
        "Patch",
        "Vendor Advisory"
      ]
    }
  ]
}