RHSA-2025:3976 - Security Advisory

Topic

An update for tigervnc is now available for Red Hat Enterprise Linux 7
Extended Lifecycle Support.

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):

• X.Org: Xwayland: Use-after-free of the root cursor (CVE-2025-26594)
• Xorg: xwayland: Buffer overflow in XkbVModMaskText() (CVE-2025-26595)
• xorg: xwayland: Heap overflow in XkbWriteKeySyms() (CVE-2025-26596)
• xorg: xwayland: Buffer overflow in XkbChangeTypesOfKey() (CVE-2025-26597)
• xorg: xwayland: Out-of-bounds write in CreatePointerBarrierClient()

(CVE-2025-26598)

• xorg: xwayland: Use of uninitialized pointer in compRedirectWindow()

(CVE-2025-26599)

• xorg: xwayland: Use-after-free in PlayReleasedEvents() (CVE-2025-26600)
• xorg: xwayland: Use-after-free in SyncInitTrigger() (CVE-2025-26601)

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

Before applying this update, make sure all previously released errata
relevant to your system have been applied.

For details on how to apply this update, refer to:

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

Affected Products

• Red Hat Enterprise Linux Server - Extended Life Cycle Support Extension 6 x86_64
• Red Hat Enterprise Linux Server - Extended Life Cycle Support Extension 6 i386
• Red Hat Enterprise Linux Server - Extended Life Cycle Support Extension (for IBM z Systems) 6 s390x

Fixes

• BZ - 2345248 - CVE-2025-26594 X.Org: Xwayland: Use-after-free of the root cursor
• BZ - 2345251 - CVE-2025-26601 xorg: xwayland: Use-after-free in SyncInitTrigger()
• BZ - 2345252 - CVE-2025-26600 xorg: xwayland: Use-after-free in PlayReleasedEvents()
• BZ - 2345253 - CVE-2025-26599 xorg: xwayland: Use of uninitialized pointer in compRedirectWindow()
• BZ - 2345254 - CVE-2025-26598 xorg: xwayland: Out-of-bounds write in CreatePointerBarrierClient()
• BZ - 2345255 - CVE-2025-26597 xorg: xwayland: Buffer overflow in XkbChangeTypesOfKey()
• BZ - 2345256 - CVE-2025-26596 xorg: xwayland: Heap overflow in XkbWriteKeySyms()
• BZ - 2345257 - CVE-2025-26595 Xorg: xwayland: Buffer overflow in XkbVModMaskText()

CVEs

• CVE-2025-26001
• CVE-2025-26594
• CVE-2025-26595
• CVE-2025-26596
• CVE-2025-26597
• CVE-2025-26598
• CVE-2025-26599
• CVE-2025-26600

References

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