FKIE_CVE-2026-4371

Vulnerability from fkie_nvd - Published: 2026-03-24 21:16 - Updated: 2026-03-27 18:05
Severity ?
7.4 (High) - CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:H
Summary
A malicious mail server could send malformed strings with negative lengths, causing the parser to read memory outside the buffer. If a mail server or connection to a mail server were compromised, an attacker could cause the parser to malfunction, potentially crashing Thunderbird or leaking sensitive data. This vulnerability affects Thunderbird < 149 and Thunderbird < 140.9.
References
security@mozilla.orghttps://bugzilla.mozilla.org/show_bug.cgi?id=2023493Permissions Required
security@mozilla.orghttps://www.mozilla.org/security/advisories/mfsa2026-23/Vendor Advisory
security@mozilla.orghttps://www.mozilla.org/security/advisories/mfsa2026-24/Vendor Advisory
Impacted products
Vendor Product Version
mozilla thunderbird *
mozilla thunderbird *
To clipboard 

{
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:mozilla:thunderbird:*:*:*:*:esr:*:*:*",
              "matchCriteriaId": "4C0558B1-4113-45A8-8E37-A0793A67AD6D",
              "versionEndExcluding": "140.9.0",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:a:mozilla:thunderbird:*:*:*:*:-:*:*:*",
              "matchCriteriaId": "40FE4697-89F1-46F6-8E28-41883647583B",
              "versionEndExcluding": "149.0",
              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "A malicious mail server could send malformed strings with negative lengths, causing the parser to read memory outside the buffer. If a mail server or connection to a mail server were compromised, an attacker could cause the parser to malfunction, potentially crashing Thunderbird or leaking sensitive data. This vulnerability affects Thunderbird \u003c 149 and Thunderbird \u003c 140.9."
    },
    {
      "lang": "es",
      "value": "Un servidor de correo malicioso podr\u00eda enviar cadenas malformadas con longitudes negativas, haciendo que el analizador lea memoria fuera del b\u00fafer. Si un servidor de correo o una conexi\u00f3n a un servidor de correo fueran comprometidos, un atacante podr\u00eda hacer que el analizador funcione mal, potencialmente bloqueando Thunderbird o filtrando datos sensibles. Esta vulnerabilidad afecta a Thunderbird \u0026lt; 149 y Thunderbird \u0026lt; 140.9."
    }
  ],
  "id": "CVE-2026-4371",
  "lastModified": "2026-03-27T18:05:16.243",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "HIGH",
          "attackVector": "NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 7.4,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "NONE",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 2.2,
        "impactScore": 5.2,
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-03-24T21:16:29.583",
  "references": [
    {
      "source": "security@mozilla.org",
      "tags": [
        "Permissions Required"
      ],
      "url": "https://bugzilla.mozilla.org/show_bug.cgi?id=2023493"
    },
    {
      "source": "security@mozilla.org",
      "tags": [
        "Vendor Advisory"
      ],
      "url": "https://www.mozilla.org/security/advisories/mfsa2026-23/"
    },
    {
      "source": "security@mozilla.org",
      "tags": [
        "Vendor Advisory"
      ],
      "url": "https://www.mozilla.org/security/advisories/mfsa2026-24/"
    }
  ],
  "sourceIdentifier": "security@mozilla.org",
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-126"
        }
      ],
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
      "type": "Secondary"
    }
  ]
}


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  • Confirmed: The vulnerability has been validated from an analyst's perspective.
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  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



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