{
  "cveId": "CVE-2026-39853",
  "url": "https://patchblox.com/security/cve/CVE-2026-39853",
  "summary": "CVE-2026-39853 is fixed in osslsigncode on 1 platform by DEBIAN-CVE-2026-39853 (version 2.12-1), released April 9, 2026. It is not reported as exploited. Patch Radar priority: High.",
  "title": "osslsigncode has a Stack Buffer Overflow via Unbounded Digest Copy During Signature Verification",
  "description": "osslsigncode is a tool that implements Authenticode signing and timestamping. Prior to 2.12, A stack buffer overflow vulnerability exists in osslsigncode in several signature verification paths. During verification of a PKCS#7 signature, the code copies the digest value from a parsed SpcIndirectDataContent structure into a fixed-size stack buffer  (mdbuf[EVP_MAX_MD_SIZE], 64 bytes) without validating that the source length fits within the destination buffer. This pattern is present in the verification handlers for PE, MSI, CAB, and script files. An attacker can craft a malicious signed file with an oversized digest field in SpcIndirectDataContent. When a user verifies such a file with osslsigncode verify, the unbounded memcpy can overflow the stack buffer and corrupt adjacent stack state. This vulnerability is fixed in 2.12.",
  "published": "2026-04-09T16:16:31Z",
  "severity": "Important",
  "cvss": 7.8,
  "cvssVector": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H",
  "cwe": "Stack-based Buffer Overflow",
  "epss": 0.00166,
  "epssPercentile": 0.05852,
  "priority": "High",
  "priorityTier": 3,
  "exploited": false,
  "vendorExploited": false,
  "disclosed": false,
  "vendorAdvisory": "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-39853",
  "fixes": [
    {
      "platform": "linux",
      "product": "osslsigncode",
      "release": "Debian 14",
      "fixedVersion": "2.12-1",
      "fix": "DEBIAN-CVE-2026-39853",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2026-39853",
      "released": "2026-04-09T16:16:31Z"
    }
  ],
  "noFixYet": [],
  "dataAsOf": "2026-11-08T13:06:02Z",
  "attribution": {
    "text": "Data: Patchblox Patch Radar",
    "url": "https://patchblox.com/security/patch-radar",
    "terms": "https://patchblox.com/security/patch-radar/use-the-data"
  }
}