{
  "fix": "RHSA-2021:4123",
  "url": "https://patchblox.com/security/fix/linux/rhsa-2021-4123",
  "summary": "RHSA-2021:4123, released November 3, 2021, fixes 8 CVEs in firefox (version 0:91.3.0-1.el8_4). None of them is reported as exploited. Patch Radar priority: High.",
  "platform": "linux",
  "type": "advisory",
  "title": "firefox security update",
  "released": "2021-11-03T00:00:00Z",
  "priority": "High",
  "priorityTier": 3,
  "priorityReason": "Closes CVE-2021-38503, high severity",
  "supported": true,
  "cveCount": 8,
  "exploitedCveCount": 0,
  "kevCveCount": 0,
  "ransomwareCveCount": 0,
  "maxEpss": 0.04116,
  "maxCvss": 10,
  "vendorAdvisory": "https://access.redhat.com/errata/RHSA-2021:4123",
  "appliesTo": [
    {
      "product": "firefox",
      "productUrl": "https://patchblox.com/security/product/linux/firefox",
      "release": "RHEL 8",
      "fixedVersion": "0:91.3.0-1.el8_4",
      "supported": true
    }
  ],
  "cves": [
    {
      "cveId": "CVE-2021-38503",
      "url": "https://patchblox.com/security/cve/CVE-2021-38503",
      "title": "Mozilla Firefox ESR and 3 others: The iframe sandbox rules were not correctly applied to XSLT stylesheets, allowing an iframe to bypass\u2026",
      "priority": "High",
      "severity": "Important",
      "cvss": 10,
      "epss": 0.04116,
      "kev": false,
      "ransomware": false,
      "exploited": false,
      "disclosed": false
    },
    {
      "cveId": "CVE-2021-38504",
      "url": "https://patchblox.com/security/cve/CVE-2021-38504",
      "title": "Mozilla Firefox ESR and 3 others: When interacting with an HTML input element\u0027s file picker dialog with webkitdirectory set, a use-after-free\u2026",
      "priority": "High",
      "severity": "Important",
      "cvss": 9.8,
      "epss": 0.01766,
      "kev": false,
      "ransomware": false,
      "exploited": false,
      "disclosed": false
    },
    {
      "cveId": "CVE-2021-38506",
      "url": "https://patchblox.com/security/cve/CVE-2021-38506",
      "title": "Mozilla Firefox ESR and 3 others: Through a series of navigations, Firefox could have entered fullscreen mode without notification or warning\u2026",
      "priority": "High",
      "severity": "Important",
      "cvss": 7.5,
      "epss": 0.01507,
      "kev": false,
      "ransomware": false,
      "exploited": false,
      "disclosed": false
    },
    {
      "cveId": "CVE-2021-43534",
      "url": "https://patchblox.com/security/cve/CVE-2021-43534",
      "title": "Mozilla Firefox ESR and 3 others: Mozilla developers and community members reported memory safety bugs present in Firefox 93 and Firefox\u2026",
      "priority": "High",
      "severity": "Important",
      "cvss": 8.8,
      "epss": 0.01248,
      "kev": false,
      "ransomware": false,
      "exploited": false,
      "disclosed": false
    },
    {
      "cveId": "CVE-2021-43535",
      "url": "https://patchblox.com/security/cve/CVE-2021-43535",
      "title": "Mozilla Firefox ESR and 3 others: A use-after-free could have occured when an HTTP2 session object was released on a different thread,\u2026",
      "priority": "High",
      "severity": "Important",
      "cvss": 8.8,
      "epss": 0.01147,
      "kev": false,
      "ransomware": false,
      "exploited": false,
      "disclosed": false
    },
    {
      "cveId": "CVE-2021-38507",
      "url": "https://patchblox.com/security/cve/CVE-2021-38507",
      "title": "Mozilla Firefox ESR and 3 others: The Opportunistic Encryption feature of HTTP2 (RFC 8164) allows a connection to be transparently upgraded\u2026",
      "priority": "High",
      "severity": "Important",
      "cvss": 7.5,
      "epss": 0.00832,
      "kev": false,
      "ransomware": false,
      "exploited": false,
      "disclosed": false
    },
    {
      "cveId": "CVE-2021-38509",
      "url": "https://patchblox.com/security/cve/CVE-2021-38509",
      "title": "Mozilla Firefox ESR and 3 others: Due to an unusual sequence of attacker-controlled events, a Javascript alert() dialog with arbitrary\u2026",
      "priority": "Routine",
      "severity": "Important",
      "cvss": 6.1,
      "epss": 0.01759,
      "kev": false,
      "ransomware": false,
      "exploited": false,
      "disclosed": false
    },
    {
      "cveId": "CVE-2021-38508",
      "url": "https://patchblox.com/security/cve/CVE-2021-38508",
      "title": "Mozilla Firefox ESR and 3 others: By displaying a form validity message in the correct location at the same time as a permission prompt\u2026",
      "priority": "Routine",
      "severity": "Important",
      "cvss": 6.1,
      "epss": 0.01642,
      "kev": false,
      "ransomware": false,
      "exploited": false,
      "disclosed": false
    }
  ],
  "dataAsOf": "2026-11-07T18:46:35Z",
  "attribution": {
    "text": "Data: Patchblox Patch Radar",
    "url": "https://patchblox.com/security/patch-radar",
    "terms": "https://patchblox.com/security/patch-radar/use-the-data"
  }
}