{"api_version":"1","generated_at":"2026-04-07T22:33:41+00:00","cve":"CVE-2026-5731","urls":{"html":"https://cve.report/CVE-2026-5731","api":"https://cve.report/api/cve/CVE-2026-5731.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-5731","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-5731"},"summary":{"title":"Memory safety bugs fixed in Firefox ESR 115.34.1, Firefox ESR 140.9.1, Thunderbird ESR 140.9.1, Firefox 149.0.2 and Thunderbird 149.0.2","description":"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 affects Firefox < 149.0.2, Firefox ESR < 115.34.1, Firefox ESR < 140.9.1, Thunderbird < 149.0.2, and Thunderbird < 140.9.1.","state":"PUBLISHED","assigner":"mozilla","published_at":"2026-04-07 13:16:47","updated_at":"2026-04-07 19:16:47"},"problem_types":["CWE-119","CWE-119 CWE-119 Improper Restriction of Operations within the Bounds of a Memory 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Grinstead, Christian Holler, Tom Schuster and the Mozilla Fuzzing Team"}],"descriptions":[{"lang":"en","supportingMedia":[{"base64":false,"type":"text/html","value":"Memory safety bugs present in Firefox ESR 115.34.0, 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 affects Firefox < 149.0.2, Firefox ESR < 115.34.1, Firefox ESR < 140.9.1, Thunderbird < 149.0.2, and Thunderbird < 140.9.1."}],"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 affects Firefox < 149.0.2, Firefox ESR < 115.34.1, Firefox ESR < 140.9.1, Thunderbird < 149.0.2, and Thunderbird < 140.9.1."}],"providerMetadata":{"dateUpdated":"2026-04-07T18:25:20.392Z","orgId":"f16b083a-5664-49f3-a51e-8d479e5ed7fe","shortName":"mozilla"},"references":[{"name":"Memory safety bugs fixed in Firefox ESR 115.34.1, Firefox ESR 140.9.1, Thunderbird ESR 140.9.1, Firefox 149.0.2 and Thunderbird 149.0.2","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"},{"url":"https://www.mozilla.org/security/advisories/mfsa2026-25/"},{"url":"https://www.mozilla.org/security/advisories/mfsa2026-26/"},{"url":"https://www.mozilla.org/security/advisories/mfsa2026-27/"},{"url":"https://www.mozilla.org/security/advisories/mfsa2026-28/"},{"url":"https://www.mozilla.org/security/advisories/mfsa2026-29/"}],"title":"Memory safety bugs fixed in Firefox ESR 115.34.1, Firefox ESR 140.9.1, Thunderbird ESR 140.9.1, Firefox 149.0.2 and Thunderbird 149.0.2"}},"cveMetadata":{"assignerOrgId":"f16b083a-5664-49f3-a51e-8d479e5ed7fe","assignerShortName":"mozilla","cveId":"CVE-2026-5731","datePublished":"2026-04-07T12:43:11.895Z","dateReserved":"2026-04-07T12:43:11.413Z","dateUpdated":"2026-04-07T18:25:20.392Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-04-07 13:16:47","lastModifiedDate":"2026-04-07 19:16:47","problem_types":["CWE-119","CWE-119 CWE-119 Improper Restriction of Operations within the Bounds of a Memory Buffer"],"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}]},"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"5731","Ordinal":"1","Title":"Memory safety bugs fixed in Firefox ESR 115.34.1, Firefox ESR 14","CVE":"CVE-2026-5731","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"5731","Ordinal":"1","NoteData":"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 affects Firefox < 149.0.2, Firefox ESR < 115.34.1, Firefox ESR < 140.9.1, Thunderbird < 149.0.2, and Thunderbird < 140.9.1.","Type":"Description","Title":"Memory safety bugs fixed in Firefox ESR 115.34.1, Firefox ESR 14"}]}}}