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{"configurations": [{"nodes": [{"cpeMatch": [{"criteria": "cpe:2.3:a:mozilla:firefox:*:*:*:*:esr:*:*:*", "matchCriteriaId": "4BA097AB-46D1-4C4E-9856-9109237940C3", "versionEndExcluding": "128.11.0", "vulnerable": true}, {"criteria": "cpe:2.3:a:mozilla:firefox:*:*:*:*:-:*:*:*", "matchCriteriaId": "E2C0FE7C-6F8E-4F1D-A768-914194586E0C", "versionEndExcluding": "139.0", "vulnerable": true}], "negate": false, "operator": "OR"}]}], "cveTags": [], "descriptions": [{"lang": "en", "value": "Script elements loading cross-origin resources generated load and error events which leaked information enabling XS-Leaks attacks. This vulnerability was fixed in Firefox 139, Firefox ESR 128.11, Thunderbird 139, and Thunderbird 128.11."}, {"lang": "es", "value": "Los elementos de script que cargaban recursos de origen cruzado generaban eventos de carga y error que filtraban informaci\u00f3n, lo que facilitaba los ataques XS-Leaks. Esta vulnerabilidad afecta a Firefox < 139 y Firefox ESR < 128.11."}], "id": "CVE-2025-5266", "lastModified": "2026-04-13T15:17:04.210", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "NONE", "baseScore": 4.3, "baseSeverity": "MEDIUM", "confidentialityImpact": "LOW", "integrityImpact": "NONE", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "REQUIRED", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N", "version": "3.1"}, "exploitabilityScore": 2.8, "impactScore": 1.4, "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary"}]}, "published": "2025-05-27T13:15:22.403", "references": [{"source": "security@mozilla.org", "tags": ["Permissions Required"], "url": "https://bugzilla.mozilla.org/show_bug.cgi?id=1965628"}, {"source": "security@mozilla.org", "tags": ["Vendor Advisory"], "url": "https://www.mozilla.org/security/advisories/mfsa2025-42/"}, {"source": "security@mozilla.org", "tags": ["Vendor Advisory"], "url": "https://www.mozilla.org/security/advisories/mfsa2025-44/"}, {"source": "security@mozilla.org", "url": "https://www.mozilla.org/security/advisories/mfsa2025-45/"}, {"source": "security@mozilla.org", "url": "https://www.mozilla.org/security/advisories/mfsa2025-46/"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "url": "https://lists.debian.org/debian-lts-announce/2025/05/msg00043.html"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "url": "https://lists.debian.org/debian-lts-announce/2025/05/msg00046.html"}], "sourceIdentifier": "security@mozilla.org", "vulnStatus": "Modified", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-200"}], "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary"}]}

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"Red Hat Enterprise Linux 8", "release_date": "2025-06-10T00:00:00Z"}, {"advisory": "RHSA-2025:8631", "cpe": "cpe:/a:redhat:rhel_aus:8.2", "package": "thunderbird-0:128.11.0-1.el8_2", "product_name": "Red Hat Enterprise Linux 8.2 Advanced Update Support", "release_date": "2025-06-09T00:00:00Z"}, {"advisory": "RHSA-2025:9075", "cpe": "cpe:/a:redhat:rhel_aus:8.2", "package": "firefox-0:128.11.0-1.el8_2", "product_name": "Red Hat Enterprise Linux 8.2 Advanced Update Support", "release_date": "2025-06-16T00:00:00Z"}, {"advisory": "RHSA-2025:8630", "cpe": "cpe:/a:redhat:rhel_aus:8.4", "package": "thunderbird-0:128.11.0-1.el8_4", "product_name": "Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support", "release_date": "2025-06-09T00:00:00Z"}, {"advisory": "RHSA-2025:9076", "cpe": "cpe:/a:redhat:rhel_aus:8.4", "package": "firefox-0:128.11.0-1.el8_4", "product_name": "Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support", "release_date": "2025-06-16T00:00:00Z"}, {"advisory": "RHSA-2025:8629", "cpe": "cpe:/a:redhat:rhel_aus:8.6", "package": "thunderbird-0:128.11.0-1.el8_6", "product_name": "Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support", "release_date": "2025-06-09T00:00:00Z"}, {"advisory": "RHSA-2025:9155", "cpe": "cpe:/a:redhat:rhel_aus:8.6", "package": "firefox-0:128.11.0-1.el8_6", "product_name": "Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support", "release_date": "2025-06-17T00:00:00Z"}, {"advisory": "RHSA-2025:8629", "cpe": "cpe:/a:redhat:rhel_tus:8.6", "package": "thunderbird-0:128.11.0-1.el8_6", "product_name": "Red Hat Enterprise Linux 8.6 Telecommunications Update Service", "release_date": "2025-06-09T00:00:00Z"}, {"advisory": "RHSA-2025:9155", "cpe": "cpe:/a:redhat:rhel_tus:8.6", "package": "firefox-0:128.11.0-1.el8_6", "product_name": "Red Hat Enterprise Linux 8.6 Telecommunications Update Service", "release_date": "2025-06-17T00:00:00Z"}, {"advisory": "RHSA-2025:8629", "cpe": "cpe:/a:redhat:rhel_e4s:8.6", "package": "thunderbird-0:128.11.0-1.el8_6", "product_name": "Red Hat Enterprise Linux 8.6 Update Services for SAP Solutions", "release_date": "2025-06-09T00:00:00Z"}, {"advisory": "RHSA-2025:9155", "cpe": "cpe:/a:redhat:rhel_e4s:8.6", "package": "firefox-0:128.11.0-1.el8_6", "product_name": "Red Hat Enterprise Linux 8.6 Update Services for SAP Solutions", "release_date": "2025-06-17T00:00:00Z"}, {"advisory": "RHSA-2025:8628", "cpe": "cpe:/a:redhat:rhel_tus:8.8", "package": "thunderbird-0:128.11.0-1.el8_8", "product_name": "Red Hat Enterprise Linux 8.8 Telecommunications Update Service", "release_date": "2025-06-09T00:00:00Z"}, {"advisory": "RHSA-2025:8628", "cpe": "cpe:/a:redhat:rhel_e4s:8.8", "package": "thunderbird-0:128.11.0-1.el8_8", "product_name": "Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions", "release_date": "2025-06-09T00:00:00Z"}, {"advisory": "RHSA-2025:9077", "cpe": "cpe:/a:redhat:rhel_e4s:8.8", "package": "firefox-0:128.11.0-1.el8_8", "product_name": "Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions", "release_date": "2025-06-16T00:00:00Z"}, {"advisory": "RHSA-2025:8293", "cpe": "cpe:/a:redhat:enterprise_linux:9", "package": "firefox-0:128.11.0-1.el9_6", "product_name": "Red Hat Enterprise Linux 9", "release_date": "2025-05-29T00:00:00Z"}, {"advisory": "RHSA-2025:8607", "cpe": "cpe:/a:redhat:enterprise_linux:9", "package": "thunderbird-0:128.11.0-1.el9_6", "product_name": "Red Hat Enterprise Linux 9", "release_date": "2025-06-05T00:00:00Z"}, {"advisory": "RHSA-2025:8598", "cpe": "cpe:/a:redhat:rhel_e4s:9.0", "package": "thunderbird-0:128.11.0-1.el9_0", "product_name": "Red Hat Enterprise Linux 9.0 Update Services for SAP Solutions", "release_date": "2025-06-05T00:00:00Z"}, {"advisory": "RHSA-2025:9073", "cpe": "cpe:/a:redhat:rhel_e4s:9.0", "package": "firefox-0:128.11.0-1.el9_0", "product_name": "Red Hat Enterprise Linux 9.0 Update Services for SAP Solutions", "release_date": "2025-06-16T00:00:00Z"}, {"advisory": "RHSA-2025:8642", "cpe": "cpe:/a:redhat:rhel_e4s:9.2", "package": "thunderbird-0:128.11.0-1.el9_2", "product_name": "Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions", "release_date": "2025-06-09T00:00:00Z"}, {"advisory": "RHSA-2025:9071", "cpe": "cpe:/a:redhat:rhel_e4s:9.2", "package": "firefox-0:128.11.0-1.el9_2", "product_name": "Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions", "release_date": "2025-06-16T00:00:00Z"}, {"advisory": "RHSA-2025:8599", "cpe": "cpe:/a:redhat:rhel_eus:9.4", "package": "thunderbird-0:128.11.0-1.el9_4", "product_name": "Red Hat Enterprise Linux 9.4 Extended Update Support", "release_date": "2025-06-05T00:00:00Z"}, {"advisory": "RHSA-2025:9072", "cpe": "cpe:/a:redhat:rhel_eus:9.4", "package": "firefox-0:128.11.0-1.el9_4", "product_name": "Red Hat Enterprise Linux 9.4 Extended Update Support", "release_date": "2025-06-16T00:00:00Z"}], "bugzilla": {"description": "firefox: thunderbird: Script element events leaked cross-origin resource status", "id": "2368755", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2368755"}, "csaw": false, "cvss3": {"cvss3_base_score": "6.1", "cvss3_scoring_vector": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N", "status": "verified"}, "cwe": "CWE-829", "details": ["Script elements loading cross-origin resources generated load and error events which leaked information enabling XS-Leaks attacks. This vulnerability affects Firefox < 139, Firefox ESR < 128.11, Thunderbird < 139, and Thunderbird < 128.11.", "A flaw was found in Firefox. The Mozilla Foundation's Security Advisory describes the following issue: Script elements loading cross-origin resources generate load and error events which can leak information enabling XS-Leaks attacks."], "name": "CVE-2025-5266", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Affected", "package_name": "rhel10/firefox-flatpak", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Affected", "package_name": "rhel10/thunderbird-flatpak", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:6", "fix_state": "Out of support scope", "package_name": "firefox", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:enterprise_linux:6", "fix_state": "Out of support scope", "package_name": "thunderbird", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Out of support scope", "package_name": "thunderbird", "product_name": "Red Hat Enterprise Linux 7"}], "public_date": "2025-05-27T12:29:25Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2025-5266\nhttps://nvd.nist.gov/vuln/detail/CVE-2025-5266\nhttps://www.mozilla.org/en-US/security/advisories/mfsa2025-44/#CVE-2025-5266\nhttps://www.mozilla.org/en-US/security/advisories/mfsa2025-46/#CVE-2025-5266"], "statement": "Red Hat Product Security rates the severity of this flaw as determined by the Mozilla Foundation Security Advisory.", "threat_severity": "Moderate"}

{"analysis": {"en": {"generated_at": "2026-04-20T17:06:25.901865+00:00", "value": {"mitigation_remediation": ["Upgrade Mozilla Firefox to at least version 139 or Firefox ESR 128.11, and upgrade Mozilla Thunderbird to at least version 139 or Thunderbird ESR 128.11.", "Enable automatic updates for all Mozilla products to ensure future patches are applied with minimal delay.", "Apply a strict Content Security Policy that limits script sources to trusted origins, which reduces the potential for cross\u2011origin script load events to leak sensitive status information.", "Monitor official Mozilla advisories for any additional mitigation steps or updates on affected platforms."], "summary": {"action": "Patch promptly", "impact": "Information Disclosure via cross\u2011origin script load events"}, "threat_synthesis": {"affected_systems": "Mozilla Firefox before version 139 and Firefox ESR before 128.11 are affected, as are Mozilla Thunderbird before version 139 and Thunderbird ESR before 128.11. No specific Red Hat product versions are directly cited as vulnerable, but the listed CPEs imply broader system compatibility for these packages.", "description_and_impact": "A vulnerability causes script elements that load resources from other origins to emit load and error events that leak status information. This leakage can be exploited to perform XS\u2011Leaks attacks, allowing an attacker to discover whether a cross\u2011origin resource exists, its status, or whether a request succeeded or failed. The primary consequence is unauthorized disclosure of information about remote resources, which could assist in crafting further attacks. The weakness is classified as CWE\u2011200 (Information Exposure).", "risk_and_exploitability": "The CVSS score of 4.3 indicates a moderate severity, and the EPSS score of less than 1% suggests the probability of exploitation is very low at present. The vulnerability is not listed in CISA\u2019s KEV catalog. The likely attack vector is a malicious web site that hosts a script element pointing to a cross\u2011origin resource; the attacker can then observe the emission of load or error events to infer status information. No privilege escalation or code execution is possible, but the disclosed information could assist in other phishing or reconnaissance activities."}}}}, "created": "2026-04-20T17:15:12.549094+00:00", "updated": "2026-04-20T17:15:12.549105+00:00", "vendors": []}