CVE-2026-4721 (GCVE-0-2026-4721)

Vulnerability from cvelistv5 – Published: 2026-03-24 12:30 – Updated: 2026-03-25 13:09
VLAI?
Title
Memory safety bugs fixed in Firefox ESR 115.34, Firefox ESR 140.9, Thunderbird ESR 140.9, Firefox 149 and Thunderbird 149
Summary
Memory safety bugs present in Firefox ESR 115.33, Firefox ESR 140.8, Thunderbird ESR 140.8, Firefox 148 and Thunderbird 148. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability affects Firefox < 149, Firefox ESR < 115.34, Firefox ESR < 140.9, Thunderbird < 149, and Thunderbird < 140.9.
Severity ?
9.8 (Critical)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CWE
  • CWE-120 - Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
Assigner
References
Impacted products
Vendor Product Version
Mozilla Firefox Affected: unspecified , < 149 (custom)
Create a notification for this product.
    Mozilla Firefox ESR Affected: unspecified , < 115.34 (custom)
Create a notification for this product.
    Mozilla Firefox ESR Affected: unspecified , < 140.9 (custom)
Create a notification for this product.
    Mozilla Thunderbird Affected: unspecified , < 149 (custom)
Create a notification for this product.
    Mozilla Thunderbird Affected: unspecified , < 140.9 (custom)
Create a notification for this product.
Credits
Christian Holler, Timothy Nikkel, Tom Schuster and the Mozilla Fuzzing Team
Show details on NVD website
To clipboard 

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "cvssV3_1": {
              "attackComplexity": "LOW",
              "attackVector": "NETWORK",
              "availabilityImpact": "HIGH",
              "baseScore": 9.8,
              "baseSeverity": "CRITICAL",
              "confidentialityImpact": "HIGH",
              "integrityImpact": "HIGH",
              "privilegesRequired": "NONE",
              "scope": "UNCHANGED",
              "userInteraction": "NONE",
              "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
              "version": "3.1"
            }
          },
          {
            "other": {
              "content": {
                "id": "CVE-2026-4721",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "total"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-03-25T03:56:11.360250Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "problemTypes": [
          {
            "descriptions": [
              {
                "cweId": "CWE-120",
                "description": "CWE-120 Buffer Copy without Checking Size of Input (\u0027Classic Buffer Overflow\u0027)",
                "lang": "en",
                "type": "CWE"
              }
            ]
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-03-25T13:09:23.842Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "Firefox",
          "vendor": "Mozilla",
          "versions": [
            {
              "lessThan": "149",
              "status": "affected",
              "version": "unspecified",
              "versionType": "custom"
            }
          ]
        },
        {
          "product": "Firefox ESR",
          "vendor": "Mozilla",
          "versions": [
            {
              "lessThan": "115.34",
              "status": "affected",
              "version": "unspecified",
              "versionType": "custom"
            }
          ]
        },
        {
          "product": "Firefox ESR",
          "vendor": "Mozilla",
          "versions": [
            {
              "lessThan": "140.9",
              "status": "affected",
              "version": "unspecified",
              "versionType": "custom"
            }
          ]
        },
        {
          "product": "Thunderbird",
          "vendor": "Mozilla",
          "versions": [
            {
              "lessThan": "149",
              "status": "affected",
              "version": "unspecified",
              "versionType": "custom"
            }
          ]
        },
        {
          "product": "Thunderbird",
          "vendor": "Mozilla",
          "versions": [
            {
              "lessThan": "140.9",
              "status": "affected",
              "version": "unspecified",
              "versionType": "custom"
            }
          ]
        }
      ],
      "credits": [
        {
          "lang": "en",
          "value": "Christian Holler, Timothy Nikkel, Tom Schuster and the Mozilla Fuzzing Team"
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "supportingMedia": [
            {
              "base64": false,
              "type": "text/html",
              "value": "Memory safety bugs present in Firefox ESR 115.33, Firefox ESR 140.8, Thunderbird ESR 140.8, Firefox 148 and Thunderbird 148. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability affects Firefox \u003c 149, Firefox ESR \u003c 115.34, Firefox ESR \u003c 140.9, Thunderbird \u003c 149, and Thunderbird \u003c 140.9."
            }
          ],
          "value": "Memory safety bugs present in Firefox ESR 115.33, Firefox ESR 140.8, Thunderbird ESR 140.8, Firefox 148 and Thunderbird 148. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability affects Firefox \u003c 149, Firefox ESR \u003c 115.34, Firefox ESR \u003c 140.9, Thunderbird \u003c 149, and Thunderbird \u003c 140.9."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-03-24T20:27:56.439Z",
        "orgId": "f16b083a-5664-49f3-a51e-8d479e5ed7fe",
        "shortName": "mozilla"
      },
      "references": [
        {
          "name": "Memory safety bugs fixed in Firefox ESR 115.34, Firefox ESR 140.9, Thunderbird ESR 140.9, Firefox 149 and Thunderbird 149",
          "url": "https://bugzilla.mozilla.org/buglist.cgi?bug_id=2013762%2C2015291%2C2016591%2C2016661%2C2016664%2C2017303%2C2017894%2C2018090%2C2018196%2C2018379%2C2019112%2C2022090%2C2022243%2C2022351%2C2022478%2C2022676"
        },
        {
          "url": "https://www.mozilla.org/security/advisories/mfsa2026-20/"
        },
        {
          "url": "https://www.mozilla.org/security/advisories/mfsa2026-21/"
        },
        {
          "url": "https://www.mozilla.org/security/advisories/mfsa2026-22/"
        },
        {
          "url": "https://www.mozilla.org/security/advisories/mfsa2026-23/"
        },
        {
          "url": "https://www.mozilla.org/security/advisories/mfsa2026-24/"
        }
      ],
      "title": "Memory safety bugs fixed in Firefox ESR 115.34, Firefox ESR 140.9, Thunderbird ESR 140.9, Firefox 149 and Thunderbird 149"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "f16b083a-5664-49f3-a51e-8d479e5ed7fe",
    "assignerShortName": "mozilla",
    "cveId": "CVE-2026-4721",
    "datePublished": "2026-03-24T12:30:44.312Z",
    "dateReserved": "2026-03-23T23:22:42.445Z",
    "dateUpdated": "2026-03-25T13:09:23.842Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-4721\",\"sourceIdentifier\":\"security@mozilla.org\",\"published\":\"2026-03-24T13:16:07.990\",\"lastModified\":\"2026-03-25T20:04:45.323\",\"vulnStatus\":\"Analyzed\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"Memory safety bugs present in Firefox ESR 115.33, Firefox ESR 140.8, Thunderbird ESR 140.8, Firefox 148 and Thunderbird 148. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability affects Firefox \u003c 149, Firefox ESR \u003c 115.34, Firefox ESR \u003c 140.9, Thunderbird \u003c 149, and Thunderbird \u003c 140.9.\"},{\"lang\":\"es\",\"value\":\"Errores de seguridad de memoria presentes en Firefox ESR 115.33, Firefox ESR 140.8, Thunderbird ESR 140.8, Firefox 148 y Thunderbird 148. Algunos de estos errores mostraron evidencia de corrupci\u00f3n de memoria y presumimos que, con suficiente esfuerzo, algunos de estos podr\u00edan haber sido explotados para ejecutar c\u00f3digo arbitrario. Esta vulnerabilidad afecta a Firefox \u0026lt; 149, Firefox ESR \u0026lt; 115.34, Firefox ESR \u0026lt; 140.9, Thunderbird \u0026lt; 149 y Thunderbird \u0026lt; 140.9.\"}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"134c704f-9b21-4f2e-91b3-4a467353bcc0\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H\",\"baseScore\":9.8,\"baseSeverity\":\"CRITICAL\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"HIGH\",\"integrityImpact\":\"HIGH\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":3.9,\"impactScore\":5.9}]},\"weaknesses\":[{\"source\":\"134c704f-9b21-4f2e-91b3-4a467353bcc0\",\"type\":\"Secondary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-120\"}]}],\"configurations\":[{\"nodes\":[{\"operator\":\"OR\",\"negate\":false,\"cpeMatch\":[{\"vulnerable\":true,\"criteria\":\"cpe:2.3:a:mozilla:firefox:*:*:*:*:esr:*:*:*\",\"versionEndExcluding\":\"115.34.0\",\"matchCriteriaId\":\"063BE653-69B0-4543-9A90-BC7A62C943B5\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:a:mozilla:firefox:*:*:*:*:-:*:*:*\",\"versionEndExcluding\":\"149.0\",\"matchCriteriaId\":\"02F2B82F-E997-4D5F-BBB0-237E4962555B\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:a:mozilla:firefox:*:*:*:*:esr:*:*:*\",\"versionStartIncluding\":\"128.0\",\"versionEndExcluding\":\"140.9.0\",\"matchCriteriaId\":\"525DEC0C-BB47-46C6-9AEB-98F27D4685FE\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:a:mozilla:thunderbird:*:*:*:*:esr:*:*:*\",\"versionEndExcluding\":\"140.9.0\",\"matchCriteriaId\":\"4C0558B1-4113-45A8-8E37-A0793A67AD6D\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:a:mozilla:thunderbird:*:*:*:*:-:*:*:*\",\"versionEndExcluding\":\"149.0\",\"matchCriteriaId\":\"40FE4697-89F1-46F6-8E28-41883647583B\"}]}]}],\"references\":[{\"url\":\"https://bugzilla.mozilla.org/buglist.cgi?bug_id=2013762%2C2015291%2C2016591%2C2016661%2C2016664%2C2017303%2C2017894%2C2018090%2C2018196%2C2018379%2C2019112%2C2022090%2C2022243%2C2022351%2C2022478%2C2022676\",\"source\":\"security@mozilla.org\",\"tags\":[\"Broken Link\"]},{\"url\":\"https://www.mozilla.org/security/advisories/mfsa2026-20/\",\"source\":\"security@mozilla.org\",\"tags\":[\"Vendor Advisory\"]},{\"url\":\"https://www.mozilla.org/security/advisories/mfsa2026-21/\",\"source\":\"security@mozilla.org\",\"tags\":[\"Vendor Advisory\"]},{\"url\":\"https://www.mozilla.org/security/advisories/mfsa2026-22/\",\"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/\",\"source\":\"security@mozilla.org\",\"tags\":[\"Vendor Advisory\"]}]}}",
    "vulnrichment": {
      "containers": "{\"adp\": [{\"title\": \"CISA ADP Vulnrichment\", \"metrics\": [{\"cvssV3_1\": {\"scope\": \"UNCHANGED\", \"version\": \"3.1\", \"baseScore\": 9.8, \"attackVector\": \"NETWORK\", \"baseSeverity\": \"CRITICAL\", \"vectorString\": \"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H\", \"integrityImpact\": \"HIGH\", \"userInteraction\": \"NONE\", \"attackComplexity\": \"LOW\", \"availabilityImpact\": \"HIGH\", \"privilegesRequired\": \"NONE\", \"confidentialityImpact\": \"HIGH\"}}, {\"other\": {\"type\": \"ssvc\", \"content\": {\"id\": \"CVE-2026-4721\", \"role\": \"CISA Coordinator\", \"options\": [{\"Exploitation\": \"none\"}, {\"Automatable\": \"no\"}, {\"Technical Impact\": \"total\"}], \"version\": \"2.0.3\", \"timestamp\": \"2026-03-25T03:56:11.360250Z\"}}}], \"problemTypes\": [{\"descriptions\": [{\"lang\": \"en\", \"type\": \"CWE\", \"cweId\": \"CWE-120\", \"description\": \"CWE-120 Buffer Copy without Checking Size of Input (\u0027Classic Buffer Overflow\u0027)\"}]}], \"providerMetadata\": {\"orgId\": \"134c704f-9b21-4f2e-91b3-4a467353bcc0\", \"shortName\": \"CISA-ADP\", \"dateUpdated\": \"2026-03-25T13:09:20.775Z\"}}], \"cna\": {\"title\": \"Memory safety bugs fixed in Firefox ESR 115.34, Firefox ESR 140.9, Thunderbird ESR 140.9, Firefox 149 and Thunderbird 149\", \"credits\": [{\"lang\": \"en\", \"value\": \"Christian Holler, Timothy Nikkel, Tom Schuster and the Mozilla Fuzzing Team\"}], \"affected\": [{\"vendor\": \"Mozilla\", \"product\": \"Firefox\", \"versions\": [{\"status\": \"affected\", \"version\": \"unspecified\", \"lessThan\": \"149\", \"versionType\": \"custom\"}]}, {\"vendor\": \"Mozilla\", \"product\": \"Firefox ESR\", \"versions\": [{\"status\": \"affected\", \"version\": \"unspecified\", \"lessThan\": \"115.34\", \"versionType\": \"custom\"}]}, {\"vendor\": \"Mozilla\", \"product\": \"Firefox ESR\", \"versions\": [{\"status\": \"affected\", \"version\": \"unspecified\", \"lessThan\": \"140.9\", \"versionType\": \"custom\"}]}, {\"vendor\": \"Mozilla\", \"product\": \"Thunderbird\", \"versions\": [{\"status\": \"affected\", \"version\": \"unspecified\", \"lessThan\": \"149\", \"versionType\": \"custom\"}]}, {\"vendor\": \"Mozilla\", \"product\": \"Thunderbird\", \"versions\": [{\"status\": \"affected\", \"version\": \"unspecified\", \"lessThan\": \"140.9\", \"versionType\": \"custom\"}]}], \"references\": [{\"url\": \"https://bugzilla.mozilla.org/buglist.cgi?bug_id=2013762%2C2015291%2C2016591%2C2016661%2C2016664%2C2017303%2C2017894%2C2018090%2C2018196%2C2018379%2C2019112%2C2022090%2C2022243%2C2022351%2C2022478%2C2022676\", \"name\": \"Memory safety bugs fixed in Firefox ESR 115.34, Firefox ESR 140.9, Thunderbird ESR 140.9, Firefox 149 and Thunderbird 149\"}, {\"url\": \"https://www.mozilla.org/security/advisories/mfsa2026-20/\"}, {\"url\": \"https://www.mozilla.org/security/advisories/mfsa2026-21/\"}, {\"url\": \"https://www.mozilla.org/security/advisories/mfsa2026-22/\"}, {\"url\": \"https://www.mozilla.org/security/advisories/mfsa2026-23/\"}, {\"url\": \"https://www.mozilla.org/security/advisories/mfsa2026-24/\"}], \"descriptions\": [{\"lang\": \"en\", \"value\": \"Memory safety bugs present in Firefox ESR 115.33, Firefox ESR 140.8, Thunderbird ESR 140.8, Firefox 148 and Thunderbird 148. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability affects Firefox \u003c 149, Firefox ESR \u003c 115.34, Firefox ESR \u003c 140.9, Thunderbird \u003c 149, and Thunderbird \u003c 140.9.\", \"supportingMedia\": [{\"type\": \"text/html\", \"value\": \"Memory safety bugs present in Firefox ESR 115.33, Firefox ESR 140.8, Thunderbird ESR 140.8, Firefox 148 and Thunderbird 148. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability affects Firefox \u003c 149, Firefox ESR \u003c 115.34, Firefox ESR \u003c 140.9, Thunderbird \u003c 149, and Thunderbird \u003c 140.9.\", \"base64\": false}]}], \"providerMetadata\": {\"orgId\": \"f16b083a-5664-49f3-a51e-8d479e5ed7fe\", \"shortName\": \"mozilla\", \"dateUpdated\": \"2026-03-24T20:27:56.439Z\"}}}",
      "cveMetadata": "{\"cveId\": \"CVE-2026-4721\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2026-03-25T13:09:23.842Z\", \"dateReserved\": \"2026-03-23T23:22:42.445Z\", \"assignerOrgId\": \"f16b083a-5664-49f3-a51e-8d479e5ed7fe\", \"datePublished\": \"2026-03-24T12:30:44.312Z\", \"assignerShortName\": \"mozilla\"}",
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}


Log in or create an account to share your comment.




Tags
Taxonomy of the tags.




Sightings

Author Source Type Date

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.