FKIE_CVE-2026-4371

Vulnerability from fkie_nvd - Published: 2026-03-24 21:16 - Updated: 2026-07-15 02:22
Severity
7.4 (High) - CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:H
8.2 (High) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/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 was fixed in 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
0b0ca135-0b70-47e7-9f44-1890c2a1c46chttps://access.redhat.com/errata/RHSA-2026:6188
0b0ca135-0b70-47e7-9f44-1890c2a1c46chttps://access.redhat.com/errata/RHSA-2026:6342
0b0ca135-0b70-47e7-9f44-1890c2a1c46chttps://access.redhat.com/errata/RHSA-2026:6917
0b0ca135-0b70-47e7-9f44-1890c2a1c46chttps://access.redhat.com/errata/RHSA-2026:8284
0b0ca135-0b70-47e7-9f44-1890c2a1c46chttps://access.redhat.com/errata/RHSA-2026:8285
0b0ca135-0b70-47e7-9f44-1890c2a1c46chttps://access.redhat.com/errata/RHSA-2026:8286
0b0ca135-0b70-47e7-9f44-1890c2a1c46chttps://access.redhat.com/errata/RHSA-2026:8287
0b0ca135-0b70-47e7-9f44-1890c2a1c46chttps://access.redhat.com/errata/RHSA-2026:8288
0b0ca135-0b70-47e7-9f44-1890c2a1c46chttps://access.redhat.com/errata/RHSA-2026:8289
0b0ca135-0b70-47e7-9f44-1890c2a1c46chttps://access.redhat.com/errata/RHSA-2026:8290
0b0ca135-0b70-47e7-9f44-1890c2a1c46chttps://access.redhat.com/errata/RHSA-2026:8315
0b0ca135-0b70-47e7-9f44-1890c2a1c46chttps://access.redhat.com/errata/RHSA-2026:8850
0b0ca135-0b70-47e7-9f44-1890c2a1c46chttps://access.redhat.com/security/cve/CVE-2026-4371
0b0ca135-0b70-47e7-9f44-1890c2a1c46chttps://bugzilla.redhat.com/show_bug.cgi?id=2451001
0b0ca135-0b70-47e7-9f44-1890c2a1c46chttps://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-4371.json
Impacted products
Vendor Product Version
mozilla thunderbird *
mozilla thunderbird *
To clipboard 

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  "cveTags": [],
  "descriptions": [
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      "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 was fixed in Thunderbird 149 and Thunderbird 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": "2026-07-15T02:22:39.793",
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          "attackVector": "NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 7.4,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "NONE",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
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          "baseScore": 8.2,
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          "confidentialityImpact": "LOW",
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          "privilegesRequired": "NONE",
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          "role": "CISA Coordinator",
          "timestamp": "2026-03-25T16:24:48.052212Z",
          "version": "2.0.3"
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  "published": "2026-03-24T21:16:29.583",
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      "tags": [
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  "vulnStatus": "Modified",
  "weaknesses": [
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          "value": "CWE-126"
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}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

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  • 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.
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  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
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  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.