RHSA-2026:99623 - Security Advisory

Topic

An update for tigervnc is now available for Red Hat Enterprise Linux 8.

Red Hat Product Security has rated this update as having a security impact of Important. A Common Vulnerability Scoring System (CVSS) base score, which gives a detailed severity rating, is available for each vulnerability from the CVE link(s) in the References section.

Description

Virtual Network Computing (VNC) is a remote display system which allows users to view a computing desktop environment not only on the machine where it is running, but from anywhere on the Internet and from a wide variety of machine architectures. TigerVNC is a suite of VNC servers and clients.

Security Fix(es):

• xorg-x11-server: xorg-x11-server: Arbitrary code execution via use-after-free in passive grab handling (CVE-2026-93516)
• xorg-x11-server: xorg-x11-server: Privilege escalation via crafted RandR provider property requests (CVE-2026-93521)
• xorg-x11-server: xwayland: xorg-x11-server: Arbitrary code execution via double-free in XKB geometry handling (CVE-2026-88812)
• xorg-x11-server: xorg-x11-server: Out-of-bounds write via unvalidated modifier in ProcXIPassiveUngrabDevice (CVE-2026-93523)
• xorg-x11-server: xorg-x11-server: arbitrary code execution via GLX RenderLarge heap-based buffer overflow (CVE-2026-93517)
• xorg-x11-server: xorg-x11-server: arbitrary code execution via integer truncation during keyboard mapping resize (CVE-2026-93518)
• xorg-x11-server: xorg-x11-server: Arbitrary code execution via buffer overflow in input_constrain_cursor() (CVE-2026-93519)
• xorg-x11-server: xorg-x11-server: arbitrary code execution via out-of-bounds write in XKB keycode handling (CVE-2026-93520)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Solution

For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

Affected Products

• Red Hat Enterprise Linux for x86_64 8 x86_64
• Red Hat Enterprise Linux for IBM z Systems 8 s390x
• Red Hat Enterprise Linux for Power, little endian 8 ppc64le
• Red Hat Enterprise Linux for ARM 64 8 aarch64
• Red Hat Enterprise Linux for x86_64 - Extended Life Cycle 8.10 x86_64
• Red Hat Enterprise Linux for ARM 64 - Extended Life Cycle 8.10 aarch64
• Red Hat Enterprise Linux for Power, little endian - Extended Life Cycle 8.10 ppc64le
• Red Hat Enterprise Linux for IBM z Systems - Extended Life Cycle 8.10 s390x

Fixes

• BZ - 2545161 - CVE-2026-93516 xorg-x11-server: xorg-x11-server: Arbitrary code execution via use-after-free in passive grab handling
• BZ - 2545164 - CVE-2026-93521 xorg-x11-server: xorg-x11-server: Privilege escalation via crafted RandR provider property requests
• BZ - 2545174 - CVE-2026-88812 xorg-x11-server: xwayland: xorg-x11-server: Arbitrary code execution via double-free in XKB geometry handling
• BZ - 2545177 - CVE-2026-93523 xorg-x11-server: xorg-x11-server: Out-of-bounds write via unvalidated modifier in ProcXIPassiveUngrabDevice
• BZ - 2545246 - CVE-2026-93517 xorg-x11-server: xorg-x11-server: arbitrary code execution via GLX RenderLarge heap-based buffer overflow
• BZ - 2545860 - CVE-2026-93518 xorg-x11-server: xorg-x11-server: arbitrary code execution via integer truncation during keyboard mapping resize
• BZ - 2545887 - CVE-2026-93519 xorg-x11-server: xorg-x11-server: Arbitrary code execution via buffer overflow in input_constrain_cursor()
• BZ - 2545908 - CVE-2026-93520 xorg-x11-server: xorg-x11-server: arbitrary code execution via out-of-bounds write in XKB keycode handling

CVEs

• CVE-2026-88812
• CVE-2026-93516
• CVE-2026-93517
• CVE-2026-93518
• CVE-2026-93519
• CVE-2026-93520
• CVE-2026-93521
• CVE-2026-93523

References

• https://access.redhat.com/security/updates/classification/#important