FKIE_CVE-2026-5731
Vulnerability from fkie_nvd - Published: 2026-04-07 13:16 - Updated: 2026-06-30 03:21
Severity
9.8 (Critical) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
8.8 (High) - CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
8.8 (High) - CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Summary
Memory safety bugs present in Firefox ESR 115.34.0, Firefox ESR 140.9.0, Thunderbird ESR 140.9.0, Firefox 149.0.1 and Thunderbird 149.0.1. 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 was fixed in Firefox 149.0.2, Firefox ESR 115.34.1, Firefox ESR 140.9.1, Thunderbird 149.0.2, and Thunderbird 140.9.1.
References
Impacted products
| Vendor | Product | Version | |
|---|---|---|---|
| mozilla | firefox | 115.34.0 | |
| mozilla | firefox | 140.9.0 | |
| mozilla | firefox | 149.0.1 | |
| mozilla | thunderbird | 140.9.0 | |
| mozilla | thunderbird | 149.0.1 |
{
"affected": [
{
"affectedData": [
{
"product": "Firefox",
"vendor": "Mozilla",
"versions": [
{
"lessThanOrEqual": "115.*",
"status": "unaffected",
"version": "115.34.1",
"versionType": "rpm"
},
{
"lessThanOrEqual": "140.*",
"status": "unaffected",
"version": "140.9.1",
"versionType": "rpm"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "149.0.2",
"versionType": "rpm"
}
]
},
{
"product": "Thunderbird",
"vendor": "Mozilla",
"versions": [
{
"lessThanOrEqual": "140.*",
"status": "unaffected",
"version": "140.9.1",
"versionType": "rpm"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "149.0.2",
"versionType": "rpm"
}
]
}
],
"source": "security@mozilla.org"
},
{
"affectedData": [
{
"cpes": [
"cpe:/o:redhat:rhel_els:7"
],
"defaultStatus": "affected",
"product": "Red Hat Enterprise Linux Server (v. 7 ELS)",
"vendor": "Red Hat"
},
{
"cpes": [
"cpe:/o:redhat:enterprise_linux_eus:10.0"
],
"defaultStatus": "affected",
"product": "Red Hat Enterprise Linux AppStream EUS (v. 10.0)",
"vendor": "Red Hat"
},
{
"cpes": [
"cpe:/o:redhat:enterprise_linux:10.1"
],
"defaultStatus": "affected",
"product": "Red Hat Enterprise Linux AppStream (v. 10)",
"vendor": "Red Hat"
},
{
"cpes": [
"cpe:/a:redhat:enterprise_linux:8::appstream"
],
"defaultStatus": "affected",
"product": "Red Hat Enterprise Linux AppStream (v. 8)",
"vendor": "Red Hat"
},
{
"cpes": [
"cpe:/a:redhat:rhel_aus:8.2::appstream"
],
"defaultStatus": "affected",
"product": "Red Hat Enterprise Linux AppStream AUS (v. 8.2)",
"vendor": "Red Hat"
},
{
"cpes": [
"cpe:/a:redhat:rhel_aus:8.4::appstream"
],
"defaultStatus": "affected",
"product": "Red Hat Enterprise Linux AppStream AUS (v.8.4)",
"vendor": "Red Hat"
},
{
"cpes": [
"cpe:/a:redhat:rhel_eus_long_life:8.4::appstream"
],
"defaultStatus": "affected",
"product": "Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.4)",
"vendor": "Red Hat"
},
{
"cpes": [
"cpe:/a:redhat:rhel_aus:8.6::appstream"
],
"defaultStatus": "affected",
"product": "Red Hat Enterprise Linux AppStream AUS (v.8.6)",
"vendor": "Red Hat"
},
{
"cpes": [
"cpe:/a:redhat:rhel_e4s:8.6::appstream"
],
"defaultStatus": "affected",
"product": "Red Hat Enterprise Linux AppStream E4S (v.8.6)",
"vendor": "Red Hat"
},
{
"cpes": [
"cpe:/a:redhat:rhel_tus:8.6::appstream"
],
"defaultStatus": "affected",
"product": "Red Hat Enterprise Linux AppStream TUS (v.8.6)",
"vendor": "Red Hat"
},
{
"cpes": [
"cpe:/a:redhat:rhel_e4s:8.8::appstream"
],
"defaultStatus": "affected",
"product": "Red Hat Enterprise Linux AppStream E4S (v.8.8)",
"vendor": "Red Hat"
},
{
"cpes": [
"cpe:/a:redhat:rhel_tus:8.8::appstream"
],
"defaultStatus": "affected",
"product": "Red Hat Enterprise Linux AppStream TUS (v.8.8)",
"vendor": "Red Hat"
},
{
"cpes": [
"cpe:/a:redhat:rhel_e4s:9.0::appstream"
],
"defaultStatus": "affected",
"product": "Red Hat Enterprise Linux AppStream E4S (v.9.0)",
"vendor": "Red Hat"
},
{
"cpes": [
"cpe:/a:redhat:rhel_e4s:9.2::appstream"
],
"defaultStatus": "affected",
"product": "Red Hat Enterprise Linux AppStream E4S (v.9.2)",
"vendor": "Red Hat"
},
{
"cpes": [
"cpe:/a:redhat:rhel_eus:9.4::appstream"
],
"defaultStatus": "affected",
"product": "Red Hat Enterprise Linux AppStream EUS (v.9.4)",
"vendor": "Red Hat"
},
{
"cpes": [
"cpe:/a:redhat:rhel_eus:9.6::appstream"
],
"defaultStatus": "affected",
"product": "Red Hat Enterprise Linux AppStream EUS (v.9.6)",
"vendor": "Red Hat"
},
{
"cpes": [
"cpe:/a:redhat:enterprise_linux:9::appstream"
],
"defaultStatus": "affected",
"product": "Red Hat Enterprise Linux AppStream (v. 9)",
"vendor": "Red Hat"
},
{
"cpes": [
"cpe:/o:redhat:enterprise_linux:10"
],
"defaultStatus": "affected",
"product": "Red Hat Enterprise Linux 10",
"vendor": "Red Hat"
},
{
"cpes": [
"cpe:/o:redhat:enterprise_linux:6"
],
"defaultStatus": "affected",
"product": "Red Hat Enterprise Linux 6",
"vendor": "Red Hat"
},
{
"cpes": [
"cpe:/o:redhat:enterprise_linux:7"
],
"defaultStatus": "affected",
"product": "Red Hat Enterprise Linux 7",
"vendor": "Red Hat"
}
],
"source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c"
}
],
"configurations": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:a:mozilla:firefox:115.34.0:*:*:*:esr:*:*:*",
"matchCriteriaId": "BAED06E5-90AA-452C-9C25-0D716D096697",
"vulnerable": true
},
{
"criteria": "cpe:2.3:a:mozilla:firefox:140.9.0:*:*:*:esr:*:*:*",
"matchCriteriaId": "923FF868-1CE2-44B6-9D9E-778599365BF8",
"vulnerable": true
},
{
"criteria": "cpe:2.3:a:mozilla:firefox:149.0.1:*:*:*:-:*:*:*",
"matchCriteriaId": "5C9EED40-0904-42A6-A3C9-9DC05CB22F2D",
"vulnerable": true
},
{
"criteria": "cpe:2.3:a:mozilla:thunderbird:140.9.0:*:*:*:esr:*:*:*",
"matchCriteriaId": "152C61D8-88E4-430C-87E7-0657C8B81EB4",
"vulnerable": true
},
{
"criteria": "cpe:2.3:a:mozilla:thunderbird:149.0.1:*:*:*:-:*:*:*",
"matchCriteriaId": "7A2F57F7-B2C0-49DB-BFCE-1C05818CB657",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "Memory safety bugs present in Firefox ESR 115.34.0, Firefox ESR 140.9.0, Thunderbird ESR 140.9.0, Firefox 149.0.1 and Thunderbird 149.0.1. 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 was fixed in Firefox 149.0.2, Firefox ESR 115.34.1, Firefox ESR 140.9.1, Thunderbird 149.0.2, and Thunderbird 140.9.1."
}
],
"id": "CVE-2026-5731",
"lastModified": "2026-06-30T03:21:08.753",
"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"
},
"exploitabilityScore": 3.9,
"impactScore": 5.9,
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"type": "Secondary"
},
{
"cvssData": {
"attackComplexity": "LOW",
"attackVector": "NETWORK",
"availabilityImpact": "HIGH",
"baseScore": 8.8,
"baseSeverity": "HIGH",
"confidentialityImpact": "HIGH",
"integrityImpact": "HIGH",
"privilegesRequired": "NONE",
"scope": "UNCHANGED",
"userInteraction": "REQUIRED",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H",
"version": "3.1"
},
"exploitabilityScore": 2.8,
"impactScore": 5.9,
"source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c",
"type": "Secondary"
}
],
"ssvcV203": [
{
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"ssvcData": {
"id": "CVE-2026-5731",
"options": [
{
"exploitation": "none"
},
{
"automatable": "no"
},
{
"technicalImpact": "total"
}
],
"role": "CISA Coordinator",
"timestamp": "2026-04-08T03:55:33.654133Z",
"version": "2.0.3"
}
}
]
},
"published": "2026-04-07T13:16:47.347",
"references": [
{
"source": "security@mozilla.org",
"tags": [
"Broken Link"
],
"url": "https://bugzilla.mozilla.org/buglist.cgi?bug_id=2021894%2C2022225%2C2022252%2C2022294%2C2023007%2C2023130%2C2023191%2C2023364%2C2023829%2C2024074%2C2024417%2C2024433%2C2024436%2C2024437%2C2024453%2C2024461%2C2024462%2C2024472%2C2024474%2C2024477%2C2025364%2C2025401%2C2025402%2C2025472%2C2026287%2C2026299%2C2026305%2C2026426"
},
{
"source": "security@mozilla.org",
"tags": [
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],
"url": "https://www.mozilla.org/security/advisories/mfsa2026-25/"
},
{
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],
"url": "https://www.mozilla.org/security/advisories/mfsa2026-26/"
},
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],
"url": "https://www.mozilla.org/security/advisories/mfsa2026-27/"
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{
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],
"url": "https://www.mozilla.org/security/advisories/mfsa2026-28/"
},
{
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"Vendor Advisory"
],
"url": "https://www.mozilla.org/security/advisories/mfsa2026-29/"
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],
"sourceIdentifier": "security@mozilla.org",
"vulnStatus": "Modified",
"weaknesses": [
{
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{
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"value": "CWE-119"
}
],
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"type": "Secondary"
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}
]
}
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
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.
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