ubuntu-cve-2026-4371
Vulnerability from osv_ubuntu
Published
2026-03-24 21:16
Modified
2026-06-30 16:18
Summary
Details

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.

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
N/A (UNKNOWN)
medium
References
To clipboard 

{
  "affected": [
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "libmozjs-52-0",
            "binary_version": "52.9.1-0ubuntu0.18.04.1"
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      },
      "package": {
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        "name": "mozjs52",
        "purl": "pkg:deb/ubuntu/mozjs52@52.9.1-0ubuntu0.18.04.1?arch=source\u0026distro=bionic"
      },
      "ranges": [
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            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "52.3.1-0ubuntu3",
        "52.3.1-7fakesync1",
        "52.8.1-0ubuntu0.18.04.1",
        "52.9.1-0ubuntu0.18.04.1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "libmozjs-38-0",
            "binary_version": "38.8.0~repack1-0ubuntu4"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:18.04:LTS",
        "name": "mozjs38",
        "purl": "pkg:deb/ubuntu/mozjs38@38.8.0~repack1-0ubuntu4?arch=source\u0026distro=bionic"
      },
      "ranges": [
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            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "38.8.0~repack1-0ubuntu1",
        "38.8.0~repack1-0ubuntu3",
        "38.8.0~repack1-0ubuntu4"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "libmozjs-68-0",
            "binary_version": "68.6.0-1ubuntu1"
          }
        ]
      },
      "package": {
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        "name": "mozjs68",
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      },
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      },
      "package": {
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      },
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          ],
          "type": "ECOSYSTEM"
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      ],
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    },
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        "ecosystem": "Ubuntu:22.04:LTS",
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      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "libmozjs-78-0",
            "binary_version": "78.15.0-4ubuntu1"
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    },
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      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "libmozjs-91-0",
            "binary_version": "91.10.0-0ubuntu1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:22.04:LTS",
        "name": "mozjs91",
        "purl": "pkg:deb/ubuntu/mozjs91@91.10.0-0ubuntu1?arch=source\u0026distro=jammy"
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    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "thunderbird",
            "binary_version": "1:140.7.1+build1-0ubuntu0.22.04.1"
          },
          {
            "binary_name": "thunderbird-gnome-support",
            "binary_version": "1:140.7.1+build1-0ubuntu0.22.04.1"
          },
          {
            "binary_name": "thunderbird-mozsymbols",
            "binary_version": "1:140.7.1+build1-0ubuntu0.22.04.1"
          },
          {
            "binary_name": "xul-ext-calendar-timezones",
            "binary_version": "1:140.7.1+build1-0ubuntu0.22.04.1"
          },
          {
            "binary_name": "xul-ext-gdata-provider",
            "binary_version": "1:140.7.1+build1-0ubuntu0.22.04.1"
          },
          {
            "binary_name": "xul-ext-lightning",
            "binary_version": "1:140.7.1+build1-0ubuntu0.22.04.1"
          }
        ]
      },
      "package": {
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        "name": "thunderbird",
        "purl": "pkg:deb/ubuntu/thunderbird@1:140.7.1+build1-0ubuntu0.22.04.1?arch=source\u0026distro=jammy"
      },
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        "1:91.3.0+build2-0ubuntu1",
        "1:91.3.1+build1-0ubuntu1",
        "1:91.3.2+build1-0ubuntu1",
        "1:91.4.0+build1.1-0ubuntu1",
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        "1:91.5.0+build1-0ubuntu1",
        "1:91.5.1+build1-0ubuntu1",
        "1:91.6.1+build1-0ubuntu1",
        "1:91.7.0+build1-0ubuntu1",
        "1:91.7.0+build2-0ubuntu1",
        "1:91.8.0+build2-0ubuntu1",
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        "1:91.11.0+build2-0ubuntu0.22.04.1",
        "1:102.2.2+build1-0ubuntu0.22.04.1",
        "1:102.4.2+build2-0ubuntu0.22.04.1",
        "1:102.7.1+build2-0ubuntu0.22.04.1",
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        "1:102.15.1+build1-0ubuntu0.22.04.1",
        "1:115.3.1+build1-0ubuntu0.22.04.2",
        "1:115.4.1+build1-0ubuntu0.22.04.1",
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      ]
    },
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      "ecosystem_specific": {
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            "binary_name": "libmozjs-102-0t64",
            "binary_version": "102.15.1-3ubuntu2"
          }
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    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "libmozjs-115-0t64",
            "binary_version": "115.10.0-1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:24.04:LTS",
        "name": "mozjs115",
        "purl": "pkg:deb/ubuntu/mozjs115@115.10.0-1?arch=source\u0026distro=noble"
      },
      "ranges": [
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            {
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        "115.7.0-4",
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    }
  ],
  "aliases": [],
  "details": "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.",
  "id": "UBUNTU-CVE-2026-4371",
  "modified": "2026-06-30T16:18:35Z",
  "published": "2026-03-24T21:16:00Z",
  "references": [
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2026-4371"
    },
    {
      "type": "REPORT",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-4371"
    },
    {
      "type": "REPORT",
      "url": "https://www.mozilla.org/en-US/security/advisories/mfsa2026-24/#CVE-2026-4371"
    },
    {
      "type": "REPORT",
      "url": "https://bugzilla.mozilla.org/show_bug.cgi?id=2023493"
    },
    {
      "type": "REPORT",
      "url": "https://www.mozilla.org/security/advisories/mfsa2026-23/"
    },
    {
      "type": "REPORT",
      "url": "https://www.mozilla.org/security/advisories/mfsa2026-24/"
    }
  ],
  "related": [],
  "schema_version": "1.7.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "medium",
      "type": "Ubuntu"
    }
  ],
  "upstream": [
    "CVE-2026-4371"
  ]
}



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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

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.


Detection rules are retrieved from Rulezet.