CVE-2026-118176

Full vulnerability record from the local CVENow database.

Description

Thunderbird's check that prevents mailbox: URLs from accessing files on remote Windows network shares could be bypassed using extended-length UNC paths. Displaying a specially crafted email could cause Thunderbird to connect to an SMB server chosen by the attacker, disclosing the user's Windows account name and NTLM authentication data, which could be used for offline password cracking or relay attacks. This bug only affects Thunderbird on Windows. Other operating systems are unaffected. This vulnerability was fixed in Thunderbird 159 and Thunderbird 153.6.

Severity

Not scored

CVSS score

Not available

Vulnerability status

Deferred

Source identifier

[email protected]

Published

2026-10-27 19:17:29.260000

Last modified

2026-10-28 14:42:32.260000

View original CVE JSON

{
  "id": "CVE-2026-118176",
  "sourceIdentifier": "[email protected]",
  "published": "2026-10-27T19:17:29.260",
  "lastModified": "2026-10-28T14:42:32.260",
  "vulnStatus": "Deferred",
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "Thunderbird's check that prevents mailbox: URLs from accessing files on remote Windows network shares could be bypassed using extended-length UNC paths. Displaying a specially crafted email could cause Thunderbird to connect to an SMB server chosen by the attacker, disclosing the user's Windows account name and NTLM authentication data, which could be used for offline password cracking or relay attacks.\nThis bug only affects Thunderbird on Windows. Other operating systems are unaffected. This vulnerability was fixed in Thunderbird 159 and Thunderbird 153.6."
    }
  ],
  "affected": [
    {
      "source": "[email protected]",
      "affectedData": [
        {
          "vendor": "Mozilla",
          "product": "Thunderbird",
          "versions": [
            {
              "version": "153.6",
              "lessThanOrEqual": "153.*",
              "versionType": "rpm",
              "status": "unaffected"
            },
            {
              "version": "159",
              "lessThanOrEqual": "*",
              "versionType": "rpm",
              "status": "unaffected"
            }
          ]
        }
      ]
    }
  ],
  "metrics": {},
  "references": [
    {
      "url": "https://bugzilla.mozilla.org/show_bug.cgi?id=2081141",
      "source": "[email protected]"
    },
    {
      "url": "https://www.mozilla.org/security/advisories/mfsa2026-121/",
      "source": "[email protected]"
    },
    {
      "url": "https://www.mozilla.org/security/advisories/mfsa2026-122/",
      "source": "[email protected]"
    }
  ]
}