SumatraPDF Update MITM -> Arbitrary Code Execution

{
  "id": "fe6540c7d70c93877d53b278a110358186472a79c1606864d02daccacc76a5e1",
  "url": "https://osv.dev/vulnerability/CVE-2026-25961",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "SumatraPDF Update MITM -> Arbitrary Code Execution",
    "summary": "SumatraPDF is a multi-format reader for Windows. In 3.5.0 through 3.5.2, SumatraPDF's update mechanism disables TLS hostname verification (INTERNET_FLAG_IGNORE_CERT_CN_INVALID) and executes installers without signature checks. A network attacker with any valid TLS certificate (e.g., Let's Encrypt) can intercept the update check request, inject a malicious installer URL, and achieve arbitrary code execution.",
    "evidence": "osv:CVE-2026-25961",
    "products": [],
    "severity": "high",
    "structured": {
      "id": "CVE-2026-25961",
      "aliases": [
        "CVE-2026-25961",
        "GHSA-xpm2-rr5m-x96q"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/sumatrapdfreader/sumatrapdf",
              "type": "GIT",
              "events": [
                {
                  "introduced": "bd84decaa54254d42dd3eda35399c5dd1b3ab57e"
                },
                {
                  "last_affected": "646d1feddcc80b3b51072c5b27a1446487904175"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "3.5.0"
                      },
                      {
                        "last_affected": "3.5.2"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StringRangeExpression"
                  },
                  {
                    "cpe": "cpe:2.3:a:sumatrapdfreader:sumatrapdf:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "3.5"
                      },
                      {
                        "last_affected": "3.5.2"
                      }
                    ],
                    "source": "CPE_RANGE"
                  }
                ]
              }
            }
          ],
          "versions": [
            "3.5.2rel",
            "3.5.1rel",
            "3.5rel"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-25961.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:45.107416500Z",
      "provider": "osv",
      "references": [
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/25xxx/CVE-2026-25961.json",
        "https://github.com/sumatrapdfreader/sumatrapdf/security/advisories/GHSA-xpm2-rr5m-x96q",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-25961"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-295",
          "CWE-494"
        ],
        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/25xxx/CVE-2026-25961.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-25961",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 513263,
  "published_at": "2026-02-09T21:34:05.203+00:00"
}