CriticalCVE-2019-8720

    WebKitGTK Memory Corruption Vulnerability (CVE-2019-8720)

    Published Last modified In CISA KEV since Sources: CVE.org

    What is affected, what to do

    A vulnerability was found in WebKit. The flaw is triggered when processing maliciously crafted web content that may lead to arbitrary code execution.

    The vulnerability is being actively exploited; treat it as a priority. Update webkitgtk to version 2.26.0, wpe_webkit to version 2.26.0. Immediate actions, mitigation and detection rules are in the runbook below.

    Affected
    • Webkitgtk eq Fixed in webkitgtk 2.26.0..Fixed in webkitgtk 2.26.0

    Not sure whether and how you are affected? Ask a question about this vulnerability

    Metrics

    8.8

    Priority

    XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.

    Source: NVD, CVSS v3

    8.8

    CVSS v3

    Severity High on the scale from 0 to 10.

    Source: CVE.org

    1.6 %

    EPSS score

    Moderate — model estimates 1-10% exploitation likelihood.

    Source: FIRST EPSS, percentile 75.0

    Show all metrics
    Severity
    Critical
    Priority (0–325)

    The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first?

    Read in glossary
    191.35 Methodology
    Exploit maturity

    An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack.

    Read in glossary
    actively exploited
    XIEM Effective CVSS

    XIEM® is the tiered managed-security operating model from NEOSEC and a registered trademark of NEOSEC GmbH. It extends classic SIEM — the central collection, normalisation and correlation of security-relevant events — with endpoint forensics, network visibility and deception technology, and consolidates them into three building tiers: Sentry, Orchestrate and Command.

    Read in glossary
    8.8 Methodology
    CVSS v3

    CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions.

    Read in glossary
    8.8
    EPSS score

    The EPSS score is the absolute model output for an individual vulnerability: the estimated probability of real-world exploitation within the next 30 days, expressed as a value between 0 and 1 (i.e. 0 % to 100 %). A score of 0.42 means „the model estimates a 42 % chance of real-world exploitation within 30 days“.

    Read in glossary
    1.6 %
    Moderate — model estimates 1-10% exploitation likelihood.
    EPSS percentile

    The EPSS percentile is the relative position of a vulnerability within all EPSS-scored CVEs, expressed as a value between 0 and 1. A percentile of 0.90 means „this CVE has a higher EPSS score than 90 % of all other scored CVEs“. Unlike the EPSS score, it is not a probability — but a positioning within a ranking.

    Read in glossary
    75.0
    High — this CVE ranks above the median of all CVEs scored today (rank ≥ 36%).
    KEV status

    The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.

    Read in glossary
    Actively exploited
    Published
    In CISA KEV since

    The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.

    Read in glossary
    CWE

    CWE is a catalogue of typical weakness types in software and hardware — such as flawed input validation, unsafe memory handling or poor authentication. Where a CVE names a concrete vulnerability in a concrete product, a CWE describes the underlying class of defect.

    Read in glossary
    CWE-119

    Response and mitigation

    Why act now?

    Prioritisation rationale

    This flaw is on KEV because crafted web content can achieve code execution in the user's context, reachable over the network without authentication. The only precondition is user interaction, such as visiting a page or opening an HTML mail. Realistic delivery is drive-by, watering-hole sites and crafted mail aimed at Linux desktops, developer workstations and embedded devices with WebKit front-ends. CISA reports no known ransomware use, and exploitation likelihood is moderate rather than top-tier. Treat it as high priority if you run a meaningful Linux desktop fleet or WebKitGTK-based kiosk/HMI systems, and close it ahead of the regular patch cycle. Headless server estates are largely unaffected but should still be cleaned up in inventory.

    1. Runbook step 1

      Immediate response (0-24 h)

      • Inventory first: Find every Linux host carrying WebKitGTK. Use rpm -qa | grep -i webkit on RHEL/Fedora (package webkit2gtk3) and dpkg -l | grep -i libwebkit2gtk on Debian/Ubuntu. Cover desktops, jump hosts, VDI golden images and kiosk devices.
      • Patch: Upgrade to WebKitGTK 2.26.0 or later. On RHEL 8 / CodeReady Linux Builder (8.0, 8.4 EUS, 8.6 EUS, including ARM64 and IBM Z), run dnf update webkit2gtk3*; look up the exact errata build in the Red Hat security advisory. On Debian/Ubuntu, run apt-get install --only-upgrade libwebkit2gtk-4.0-37.
      • Restart consumers: Running processes keep the vulnerable library mapped after the upgrade. Close Epiphany (GNOME Web), Evolution, Geary, Yelp, Liferea and any app with an embedded WebView. Find stale processes with needs-restarting (RHEL) or lsof | grep -i webkit | grep DEL.
      • Stopgap for unpatchable hosts: Remove or policy-block WebKitGTK-based browsers and move users to a maintained browser (Firefox ESR/Chromium). Force plain-text rendering in Evolution and disable remote content loading.
      • Compromise check: Review process ancestry on hosts that ran the vulnerable library against untrusted web or mail content (see Detection rules). On any hit, isolate the host and rotate the user's credentials: SSH keys, browser sessions and mail passwords.

    2. Runbook step 2

      Mitigation layers

      • Network / proxy: Force Linux workstation web traffic through an inspecting forward proxy and block malvertising and exploit-kit categories. Deny direct outbound 80/443 at the perimeter firewall.
      • Mail gateway: Quarantine or sanitise (CDR) HTML mail carrying embedded script, inline SVG or oversized base64 image payloads. Evolution and Geary render through WebKitGTK, so mail is a delivery path.
      • Endpoint hardening: Confine WebKitGTK apps with a Flatpak sandbox or an AppArmor/SELinux profile. Deny execve of shells, curl, wget, python* and nc from WebKitWebProcess and WebKitNetworkProcess. Keep WebKit's bubblewrap sandbox enabled: do not disable WEBKIT_FORCE_SANDBOX and never run these apps as root.
      • IAM / least privilege: Run desktop users without sudo. Ban web browsing on admin and jump hosts so that user-context code execution does not land directly on privileged access.
      • Embedded/kiosk configuration: Restrict kiosk, signage and HMI devices with WebKitGTK front-ends (relevant in KRITIS environments) to an allowlist of internal URLs. Enforce this via proxy ACL or a host firewall until the vendor ships updated firmware.

    3. Runbook step 3

      Detection rules

      • Process ancestry (auditd / Sysmon for Linux EID 1 / EDR): Alert when WebKitWebProcess spawns a shell or downloader. Sigma shape: ParentImage|endswith: '/WebKitWebProcess' AND Image|endswith: ['/sh','/bash','/dash','/curl','/wget','/python3','/nc']. For auditd, use -a always,exit -F arch=b64 -S execve -k webkit_exec and then join on ppid.
      • Crash telemetry (journald / systemd-coredump): Clusters of WebKitWebProcess core dumps with SIGSEGV/SIGBUS often indicate failed exploitation attempts. Query with journalctl -t systemd-coredump | grep -i WebKitWebProcess and correlate with the last URL visited or mail opened.
      • File system (auditd / EDR FIM): Flag writes by the WebKit process outside its cache. Watch ~/.config/autostart/, ~/.bashrc, ~/.ssh/authorized_keys, executable files in /tmp, and ~/.local/share/systemd/user/. These are classic persistence footholds after code execution.
      • Network (Zeek/Suricata): Look for Linux clients opening connections on non-standard ports, or to newly registered domains, shortly after HTTP fetches from ad networks or unknown domains. Zeek approach: match conn.log entries with id.resp_p !in {80,443} from the Linux client subnet within 60 s of an http.log entry.
      • Inventory drift (SIEM): Alert on WebKitGTK versions below 2.26.0 in package telemetry (Satellite, osquery deb_packages/rpm_packages). SPL: index=inventory package="*webkit2gtk*" | where version<"2.26.0".

    Detection rules

    No NEOSEC detection rule is available for this vulnerability yet.

    Classification under NIS2 and CRA

    Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.

    NIS2

    NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management.

    Read in glossary
    Actively exploited: treat the vulnerability as a priority in vulnerability handling under Art. 21(2)(e) NIS2. If it is exploited in your environment, check the reporting obligation under Art. 23 (early warning within 24 hours).
    CRA

    The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates.

    Read in glossary
    Since 11.09.2026, manufacturers of affected products with digital elements must report actively exploited vulnerabilities under Art. 14 CRA, with an early warning within 24 hours via ENISA's single reporting platform.
    ISO/IEC 27001

    ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security.

    Read in glossary
    Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.

    Description

    A vulnerability was found in WebKit. The flaw is triggered when processing maliciously crafted web content that may lead to arbitrary code execution. Improved memory handling addresses the multiple memory corruption issues.

    Source: NVD (NIST), cvelistv5, CISA KEV Catalog

    Affected products

    The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.

    Affected products
    Affected versionsFixed in
    —webkitgtk
    • Fixed in webkitgtk 2.26.0
    • —
    redhatcodeready_linux_builder
    • 8.0
    • —
    redhatcodeready_linux_builder_eus
    • 8.4
    • 8.6
    • —
    • —
    redhatcodeready_linux_builder_for_arm64_eus
    • 8.6
    • 8.4
    • 8.0
    • —
    • —
    • —
    redhatcodeready_linux_builder_for_ibm_z_systems_eus
    • 8.4
    • 8.6
    • 8.0
    • —
    • —
    • —
    redhatcodeready_linux_builder_for_power_little_endian_eus
    • 8.4
    • 8.0
    • 8.6
    • —
    • —
    • —
    webkitgtkwebkitgtk
    • < 2.26.0
    • 2.26.0
    wpewebkitwpe_webkit
    • < 2.26.0
    • 2.26.0

    Vendors and products

    Affected operating systems

    Affected operating systems
    Linuxredhatenterprise_linux8.0
    Linuxredhatenterprise_linux_desktop7.0
    Linuxredhatenterprise_linux_eus8.4
    Linuxredhatenterprise_linux_eus8.6
    Linuxredhatenterprise_linux_for_arm64_eus8.6
    Linuxredhatenterprise_linux_for_ibm_z_systems7.0
    Linuxredhatenterprise_linux_for_ibm_z_systems8.0
    Linuxredhatenterprise_linux_for_ibm_z_systems_eus8.4
    Linuxredhatenterprise_linux_for_ibm_z_systems_eus8.6
    Linuxredhatenterprise_linux_for_power_big_endian7.0
    Linuxredhatenterprise_linux_for_power_little_endian7.0
    Linuxredhatenterprise_linux_for_power_little_endian8.0
    Linuxredhatenterprise_linux_for_power_little_endian_eus8.4
    Linuxredhatenterprise_linux_for_power_little_endian_eus8.6
    Linuxredhatenterprise_linux_for_scientific_computing7.0
    Linuxredhatenterprise_linux_server7.0
    Linuxredhatenterprise_linux_server_aus8.4
    Linuxredhatenterprise_linux_server_aus8.6
    Linuxredhatenterprise_linux_server_for_power_little_endian_update_services_for_sap_solutions8.4
    Linuxredhatenterprise_linux_server_for_power_little_endian_update_services_for_sap_solutions8.6
    Linuxredhatenterprise_linux_server_tus8.4
    Linuxredhatenterprise_linux_server_tus8.6
    Linuxredhatenterprise_linux_server_update_services_for_sap_solutions8.4
    Linuxredhatenterprise_linux_server_update_services_for_sap_solutions8.6

    Weakness classes (CWE)

    • CWE-119Improper Restriction of Operations within the Bounds of a Memory Buffer

      Class

      The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.

      Entry at MITRE CWE-119

    Public exploit references

    Publicly reported proof-of-concepts, exploit modules and detection templates for this vulnerability. NEOSEC links to the original sources only and does not provide any exploit code.

    Public exploit references
    CISA KEV CatalogCISA Known Exploited Vulnerability (opens in a new tab)cisa.govactively exploited

    References & sources

    Changes to this CVE

    Who changed this CVE and when: NVD (analysis, affected products, CVSS), the CVE publisher (CNA) and additional providers such as CISA (ADP).

    1. NVD analysis modifiedNVD

    2. Record modifiedRed Hat

      Show 6 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Referenceadded
      —
      https://bugzilla.redhat.com/show_bug.cgi?id=1876611
      Referenceadded
      —
      https://webkitgtk.org/security/WSA-2019-0005.html
      Referenceremoved
      https://bugzilla.redhat.com/show_bug.cgi?id=1876611
      —
      Referenceremoved
      https://webkitgtk.org/security/WSA-2019-0005.html
      —
      Reference typeremoved
      https://bugzilla.redhat.com/show_bug.cgi?id=1876611 Types: Issue Tracking, Third Party Advisory
      —
      Reference typeremoved
      https://webkitgtk.org/security/WSA-2019-0005.html Types: Vendor Advisory
      —

      Source identifier: secalert@redhat.com

    3. Record modifiedCISA ADP

      Show 4 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Weakness type (CWE)removed
      CWE-119
      —
      Referenceadded
      —
      https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2019-8720
      Referenceremoved
      https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2019-8720
      —
      Reference typeremoved
      https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2019-8720 Types: US Government Resource
      —

      Source identifier: 134c704f-9b21-4f2e-91b3-4a467353bcc0

    4. Record modifiedCVE Program

      Show 6 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Referenceadded
      —
      https://bugzilla.redhat.com/show_bug.cgi?id=1876611
      Referenceadded
      —
      https://webkitgtk.org/security/WSA-2019-0005.html
      Referenceremoved
      https://bugzilla.redhat.com/show_bug.cgi?id=1876611
      —
      Referenceremoved
      https://webkitgtk.org/security/WSA-2019-0005.html
      —
      Reference typeremoved
      https://bugzilla.redhat.com/show_bug.cgi?id=1876611 Types: Issue Tracking, Third Party Advisory
      —
      Reference typeremoved
      https://webkitgtk.org/security/WSA-2019-0005.html Types: Vendor Advisory
      —

      Source identifier: af854a3a-2127-422b-91ae-364da2661108

    Embed badge

    Show the severity and KEV status of this vulnerability on your site – with a link back here. The image is updated hourly.

    Badge preview for CVE-2019-8720
    <a href="https://intel.neosec.eu/en/cve/CVE-2019-8720"><img src="https://intel.neosec.eu/badge/cve/CVE-2019-8720.svg?lang=en" alt="CVE-2019-8720 – NEOSEC Intel" height="20"></a>