Vulnerability-Lookup

FKIE_CVE-2026-4720

Vulnerability from fkie_nvd - Published: 2026-03-24 13:16 - Updated: 2026-03-25 20:56

Severity ?

9.8 (Critical) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Summary

Memory safety bugs present in 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 < 140.9, Thunderbird < 149, and Thunderbird < 140.9.

References

URL	Tags
security@mozilla.org	https://bugzilla.mozilla.org/buglist.cgi?bug_id=2004652%2C2019372%2C2021922%2C2022567%2C2022733	Broken Link
security@mozilla.org	https://www.mozilla.org/security/advisories/mfsa2026-20/	Vendor Advisory
security@mozilla.org	https://www.mozilla.org/security/advisories/mfsa2026-22/	Vendor Advisory
security@mozilla.org	https://www.mozilla.org/security/advisories/mfsa2026-23/	Vendor Advisory
security@mozilla.org	https://www.mozilla.org/security/advisories/mfsa2026-24/	Vendor Advisory

Impacted products

Vendor	Product	Version
mozilla	firefox	*
mozilla	firefox	*
mozilla	thunderbird	*
mozilla	thunderbird	*

JSON

To clipboard

{
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:mozilla:firefox:*:*:*:*:esr:*:*:*",
              "matchCriteriaId": "DA62D95E-CB01-4586-83DB-5094116FC939",
              "versionEndExcluding": "140.9.0",
              "vulnerable": true
            },
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  "descriptions": [
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      "lang": "en",
      "value": "Memory safety bugs present in 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 140.9, Thunderbird \u003c 149, and Thunderbird \u003c 140.9."
    },
    {
      "lang": "es",
      "value": "Errores de seguridad de memoria presentes en 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; 140.9, Thunderbird \u0026lt; 149 y Thunderbird \u0026lt; 140.9."
    }
  ],
  "id": "CVE-2026-4720",
  "lastModified": "2026-03-25T20:56:19.130",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "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"
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        "exploitabilityScore": 3.9,
        "impactScore": 5.9,
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "type": "Secondary"
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  },
  "published": "2026-03-24T13:16:07.893",
  "references": [
    {
      "source": "security@mozilla.org",
      "tags": [
        "Broken Link"
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      "url": "https://bugzilla.mozilla.org/buglist.cgi?bug_id=2004652%2C2019372%2C2021922%2C2022567%2C2022733"
    },
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    },
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    },
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      "tags": [
        "Vendor Advisory"
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      "url": "https://www.mozilla.org/security/advisories/mfsa2026-23/"
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      "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-120"
        }
      ],
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
      "type": "Secondary"
    }
  ]
}

CVE-2026-4720 (GCVE-0-2026-4720)

Vulnerability from cvelistv5 – Published: 2026-03-24 12:30 – Updated: 2026-03-25 13:10

Title

Memory safety bugs fixed in Firefox ESR 140.9, Thunderbird ESR 140.9, Firefox 149 and Thunderbird 149

Summary

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

mozilla

References

URL

Tags

	https://bugzilla.mozilla.org/buglist.cgi?bug_id=2…
	https://www.mozilla.org/security/advisories/mfsa2…
	https://www.mozilla.org/security/advisories/mfsa2…
	https://www.mozilla.org/security/advisories/mfsa2…
	https://www.mozilla.org/security/advisories/mfsa2…

Impacted products

Vendor

Product

Version

Mozilla

Firefox

Affected: unspecified , < 149 (custom)

Mozilla	Firefox ESR	Affected: unspecified , < 140.9 (custom)
Mozilla	Thunderbird	Affected: unspecified , < 149 (custom)
Mozilla	Thunderbird	Affected: unspecified , < 140.9 (custom)

Credits

Christian Holler, Gabriele Svelto, Tom Schuster and the Mozilla Fuzzing Team

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
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        "metrics": [
          {
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              "attackComplexity": "LOW",
              "attackVector": "NETWORK",
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              "baseScore": 9.8,
              "baseSeverity": "CRITICAL",
              "confidentialityImpact": "HIGH",
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              "userInteraction": "NONE",
              "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
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            }
          },
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                "id": "CVE-2026-4720",
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                    "Exploitation": "none"
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                  },
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                    "Technical Impact": "total"
                  }
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                "role": "CISA Coordinator",
                "timestamp": "2026-03-25T03:56:10.337285Z",
                "version": "2.0.3"
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                "lang": "en",
                "type": "CWE"
              }
            ]
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-03-25T13:10:13.381Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
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    "cna": {
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            }
          ],
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        },
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          "url": "https://www.mozilla.org/security/advisories/mfsa2026-20/"
        },
        {
          "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/"
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      "title": "Memory safety bugs fixed in Firefox ESR 140.9, Thunderbird ESR 140.9, Firefox 149 and Thunderbird 149"
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    "datePublished": "2026-03-24T12:30:43.271Z",
    "dateReserved": "2026-03-23T23:22:41.974Z",
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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.

Action not permitted

FKIE_CVE-2026-4720

CVE-2026-4720 (GCVE-0-2026-4720)

Tags

Sightings

Nomenclature