CVE-2020-13962:OpenSSL Error Queue Mishandling in Qt 5.12.2 through 5.14.2 Causing Denial of Service

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Qt 5.12.2 through 5.14.2 contains a vulnerability in how it handles OpenSSL's error queue. This mishandling can cause a denial of service to QSslSocket users, as errors from one TLS session can leak into unrelated sessions, potentially causing unrelated sessions to be disconnected when any handshake fails. This issue affects unofficial builds of Mumble 1.3.0 and other products that use the affected Qt versions. Mumble 1.3.1 is not affected by this vulnerability, regardless of the Qt version being used.

Overview

The vulnerability (CVE-2020-13962) exists in Qt versions 5.12.2 through 5.14.2 and affects applications using QSslSocket. The core issue is improper management of OpenSSL's error queue, which causes errors from failed TLS handshakes to persist and affect subsequent, unrelated TLS sessions. When a handshake fails in one session, it can trigger disconnections in other, unrelated sessions, resulting in a denial of service condition. This vulnerability particularly impacts unofficial builds of Mumble 1.3.0, though the official Mumble 1.3.1 release has implemented fixes to mitigate this issue regardless of the Qt version being used.

Remediation

To remediate this vulnerability, the following actions are recommended:

  1. Update to Qt versions that have fixed this issue.
  2. If using Mumble, upgrade to version 1.3.1 or later, which contains fixes for this issue.
  3. For developers using Qt with OpenSSL, ensure proper error queue management by clearing the OpenSSL error queue after handling errors and before starting new TLS sessions.
  4. Apply the patches referenced in the GitHub pull request (https://github.com/mumble-voip/mumble/pull/4032) if you maintain a Qt-based application affected by this issue.
  5. Follow distribution-specific updates as mentioned in the Fedora, openSUSE, and Gentoo security advisories.

References

  1. Qt Bug Tracker: https://bugreports.qt.io/browse/QTBUG-83450
  2. Mumble Issue Tracker: https://github.com/mumble-voip/mumble/issues/3679
  3. Mumble Fix Pull Request: https://github.com/mumble-voip/mumble/pull/4032
  4. Fedora Security Advisories:
    • https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/4X6EDPIIAQPVP2CHL2CHDHJ25EECA7UE/
    • https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/UQJDBZUYMMF4R5QQKD2HTIKQU2NSKO63/
    • https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/V3IZY7LKJ6NAXQDFYFR4S7L5BBHYK53K/
  5. Gentoo Security Advisory: https://security.gentoo.org/glsa/202007-18
  6. openSUSE Security Advisory: http://lists.opensuse.org/opensuse-security-announce/2020-09/msg00004.html

Industry ExposureMost to least
This section illustrates the prevalence of a specific Common Vulnerabilities and Exposures (CVE) across various industries based on customer reports. The ranking displays industries from the most to least affected by this particular vulnerability, offering valuable insight into where this CVE has been most frequently observed. This information can help organizations within these sectors prioritize their security efforts, understand their relative risk exposure compared to their peers, and focus remediation strategies where they are most needed. By understanding the industry-specific impact, organizations can make more informed decisions regarding patching, resource allocation, and overall risk management related to this CVE.

  1. Manufacturing
    Manufacturing
  2. Health Care & Social Assistance
    Health Care & Social Assistance
  3. Educational Services
    Educational Services
  4. Information
    Information
  5. Professional, Scientific, & Technical Services
    Professional, Scientific, & Technical Services
  6. Other Services (except Public Administration)
    Other Services (except Public Administration)
  7. Retail Trade
    Retail Trade
  8. Transportation & Warehousing
    Transportation & Warehousing
  9. Arts, Entertainment & Recreation
    Arts, Entertainment & Recreation
  10. Finance and Insurance
    Finance and Insurance
  11. Management of Companies & Enterprises
    Management of Companies & Enterprises
  12. Public Administration
    Public Administration
  13. Accommodation & Food Services
    Accommodation & Food Services
  14. Administrative, Support, Waste Management & Remediation Services
    Administrative, Support, Waste Management & Remediation Services
  15. Agriculture, Forestry Fishing & Hunting
    Agriculture, Forestry Fishing & Hunting
  16. Construction
    Construction
  17. Mining
    Mining
  18. Real Estate Rental & Leasing
    Real Estate Rental & Leasing
  19. Utilities
    Utilities
  20. Wholesale Trade
    Wholesale Trade

Focus on What Matters

  1. See Everything.
  2. Identify True Risk.
  3. Proactively Mitigate Threats.

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