Vulnerability-Lookup

GHSA-G4VF-4V95-X4PC

Vulnerability from github – Published: 2026-10-27 21:33 – Updated: 2026-10-27 21:33

Details

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.

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{
  "affected": [],
  "aliases": [
    "CVE-2026-118176"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-10-27T19:17:29Z",
    "severity": null
  },
  "details": "Thunderbird\u0027s 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\u0027s 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.",
  "id": "GHSA-g4vf-4v95-x4pc",
  "modified": "2026-10-27T21:33:41Z",
  "published": "2026-10-27T21:33:41Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-118176"
    },
    {
      "type": "WEB",
      "url": "https://bugzilla.mozilla.org/show_bug.cgi?id=2081141"
    },
    {
      "type": "WEB",
      "url": "https://www.mozilla.org/security/advisories/mfsa2026-121"
    },
    {
      "type": "WEB",
      "url": "https://www.mozilla.org/security/advisories/mfsa2026-122"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}

CVE-2026-118176 (GCVE-0-2026-118176)

Vulnerability from cvelistv5 – Published: 2026-10-27 18:16 – Updated: 2026-10-27 18:27

Title

Bypass of remote UNC path restriction in mailbox: URLs

Summary

Severity

No CVSS data available.

Assigner

mozilla CNA under the mitre root

CNA scorecard E 38/100 over 683 records in the last 180 days details

References

3 references

URL	Tags
https://bugzilla.mozilla.org/show_bug.cgi?id=2081141
https://www.mozilla.org/security/advisories/mfsa2…
https://www.mozilla.org/security/advisories/mfsa2…

Impacted products

1 product

Vendor	Product	Version
Mozilla	Thunderbird	Unaffected: 153.6 , ≤ 153.* (rpm) Unaffected: 159 , ≤ * (rpm)

Credits

YuYoung Sung

Show details on NVD website

JSON

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{
  "containers": {
    "cna": {
      "affected": [
        {
          "product": "Thunderbird",
          "vendor": "Mozilla",
          "versions": [
            {
              "lessThanOrEqual": "153.*",
              "status": "unaffected",
              "version": "153.6",
              "versionType": "rpm"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "159",
              "versionType": "rpm"
            }
          ]
        }
      ],
      "credits": [
        {
          "lang": "en",
          "value": "YuYoung Sung"
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "supportingMedia": [
            {
              "base64": false,
              "type": "text/html",
              "value": "Thunderbird\u0027s 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\u0027s Windows account name and NTLM authentication data, which could be used for offline password cracking or relay attacks.\u003cbr /\u003eThis bug only affects Thunderbird on Windows. Other operating systems are unaffected. This vulnerability was fixed in Thunderbird 159 and Thunderbird 153.6."
            }
          ],
          "value": "Thunderbird\u0027s 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\u0027s 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."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-27T18:27:48.875Z",
        "orgId": "f16b083a-5664-49f3-a51e-8d479e5ed7fe",
        "shortName": "mozilla"
      },
      "references": [
        {
          "url": "https://bugzilla.mozilla.org/show_bug.cgi?id=2081141"
        },
        {
          "url": "https://www.mozilla.org/security/advisories/mfsa2026-121/"
        },
        {
          "url": "https://www.mozilla.org/security/advisories/mfsa2026-122/"
        }
      ],
      "title": "Bypass of remote UNC path restriction in mailbox: URLs"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "f16b083a-5664-49f3-a51e-8d479e5ed7fe",
    "assignerShortName": "mozilla",
    "cveId": "CVE-2026-118176",
    "datePublished": "2026-10-27T18:16:30.272Z",
    "dateReserved": "2026-10-27T18:16:29.898Z",
    "dateUpdated": "2026-10-27T18:27:48.875Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Vulnerability timeline

Sightings and recorded dates, grouped by day · UTC

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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

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