Summary
X.Org is an open-source implementation of the X Window System. It provides the basic low-level functionality that full-fledged graphical user interfaces are designed upon.
Security Fix(es):
* xorg: xwayland: X.Org X server: Denial of Service via integer underflow in XKB compatibility map handling (CVE-2026-33999)
* xorg: xwayland: X.Org X server: Use-after-free vulnerability leads to server crash and potential memory corruption (CVE-2026-34001)
* xorg: xwayland: X.Org X server: Information exposure and denial of service via out-of-bounds memory access (CVE-2026-34003)
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.
Fixed packages 8
| Release | Package | Fixed in |
|---|---|---|
| AlmaLinux · 9 | xorg-x11-server-common | 1.20.11-34.el9_8 |
| AlmaLinux · 9 | xorg-x11-server-devel | 1.20.11-34.el9_8 |
| AlmaLinux · 9 | xorg-x11-server-source | 1.20.11-34.el9_8 |
| AlmaLinux · 9 | xorg-x11-server-Xdmx | 1.20.11-34.el9_8 |
| AlmaLinux · 9 | xorg-x11-server-Xephyr | 1.20.11-34.el9_8 |
| AlmaLinux · 9 | xorg-x11-server-Xnest | 1.20.11-34.el9_8 |
| AlmaLinux · 9 | xorg-x11-server-Xorg | 1.20.11-34.el9_8 |
| AlmaLinux · 9 | xorg-x11-server-Xvfb | 1.20.11-34.el9_8 |
Vulnerabilities 3
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High 7.8
Xorg: xwayland: x.org x server: denial of service via integer underflow in xkb compatibility map handling
A flaw was found in the X.Org X server. This integer underflow vulnerability, specifically in the XKB compatibility map handling, allows an attacker with local or remote X11 server access to trigger a buffer read overrun. This can lead to memory-safety violat…
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High 7.8
Xorg: xwayland: x.org x server: use-after-free vulnerability leads to server crash and potential memory corruption
A flaw was found in the X.Org X server. This use-after-free vulnerability occurs in the XSYNC fence triggering logic, specifically within the miSyncTriggerFence() function. An attacker with access to the X11 server can exploit this without user interaction, l…
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High 7.8
Xorg: xwayland: x.org x server: information exposure and denial of service via out-of-bounds memory access
A flaw was found in the X.Org X server's XKB key types request validation. A local attacker could send a specially crafted request to the X server, leading to an out-of-bounds memory access vulnerability. This could result in the disclosure of sensitive infor…
References
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report
https://access.redhat.com/security/cve/CVE-2026-33999
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report
https://access.redhat.com/security/cve/CVE-2026-34001
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report
https://access.redhat.com/security/cve/CVE-2026-34003
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report
https://bugzilla.redhat.com/2451106
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report
https://bugzilla.redhat.com/2451109
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report
https://bugzilla.redhat.com/2451113
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advisory
https://errata.almalinux.org/9/ALSA-2026-19343.html