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High ALAS2-2026-3336 9 CVEs

Important: xorg-x11-server security update (Amazon Linux 2)

Published Jun 8, 2026 · Updated Jun 12, 2026

Ecosystem: Amazon Linux

Summary

Package updates are available for Amazon Linux 2 that fix the following vulnerabilities: CVE-2026-50264: An out-of-bounds write flaw was found in the X.Org X server and Xwayland in DRIGetBuffers/DRIGetBuffersWithFormat. A client that requests multiple DRI2BufferBackLeft attachments and one DRI2BufferFrontLeft can trigger an out-of-bounds heap write. This may be used to crash the server, or for privilege escalation if the X server runs as root. CVE-2026-50263: A use-after-free flaw was found in the X.Org X server and Xwayland in CreateSaverWindow(). A client can trigger a use-after-free read after changing window attributes and forcing the screen saver, leading to information disclosure. CVE-2026-50262: Multiple issues have been found in the X server and Xwayland implementations published by X.Org for which we are releasing security fixes for in xorg-server-21.1.23 and xwayland-24.1.12. CVE-2026-50261: A use-after-free flaw was found in the X.Org X server and Xwayland in SyncChangeCounter(). A client that sets up multiple SyncCounters can trigger a use-after-free when destroying those counters via a second client connection while changing those counters. This may be used to crash the server, or for privilege escalation if the X server runs as root. CVE-2026-50260: A use-after-free flaw was found in the X.Org X server and Xwayland in FreeCounter(). A client that sets up multiple SyncCounters and awaits on those triggers can trigger a use-after-free when destroying those counters via a second client connection. This may be used to crash the server, or for privilege escalation if the X server runs as root. CVE-2026-50259: A stack-based buffer overflow flaw was found in the X.Org X server and Xwayland. _XkbSetMapChecks() declares a fixed-size stack buffer mapWidths[256] indexed by key type index. The helper function CheckKeyTypes() writes to this buffer at a client-controlled offset, allowing a stack buffer overflow. This may be used to crash the server, or for privilege escalation if the X server runs as root. CVE-2026-50258: A stack-based buffer overflow flaw was found in the X.Org X server and Xwayland. The X server has multiple stack buffers sized XkbMaxShiftLevel * XkbNumKbdGroups but CheckKeyTypes() does not verify or clamp non-canonical key types to XkbMaxShiftLevel. A client can change key types to excessive shift levels and trigger stack overflows. This is caused by an incomplete fix of CVE-2025-26597. This may be used to crash the server, or for privilege escalation if the X server runs as root. CVE-2026-50257: A use-after-free flaw was found in the X.Org X server and Xwayland in miSyncDestroyFence(). A client that sets up multiple fence triggers can trigger a use-after-free function pointer call. An attacker would connect to the X server to set up a fence and await that fence, then a second X connection destroys the fence, causing the use-after-free. This may be used to crash the server, or for privilege escalation if the X server runs as root. CVE-2026-50256: A stack-based buffer overflow flaw was found in the X.Org X server and Xwayland. A mismatch between the X server and the libXfont2 library's maximum font name length can cause a stack buffer overflow during font alias resolution. The server allocates a 256 byte stack buffer but libXfont2's alias target name length is 1024 bytes. A font alias name between 257 and 1023 bytes causes the X server to copy that name into the undersized stack buffer without further checks. This may be used to crash the server, or for privilege escalation if the X server runs as root.

Fixed packages 10

ReleasePackageFixed in
Amazon Linux · 2 xorg-x11-server-common 0:1.20.4-22.amzn2.0.12
Amazon Linux · 2 xorg-x11-server-debuginfo 0:1.20.4-22.amzn2.0.12
Amazon Linux · 2 xorg-x11-server-devel 0:1.20.4-22.amzn2.0.12
Amazon Linux · 2 xorg-x11-server-source 0:1.20.4-22.amzn2.0.12
Amazon Linux · 2 xorg-x11-server-Xdmx 0:1.20.4-22.amzn2.0.12
Amazon Linux · 2 xorg-x11-server-Xephyr 0:1.20.4-22.amzn2.0.12
Amazon Linux · 2 xorg-x11-server-Xnest 0:1.20.4-22.amzn2.0.12
Amazon Linux · 2 xorg-x11-server-Xorg 0:1.20.4-22.amzn2.0.12
Amazon Linux · 2 xorg-x11-server-Xvfb 0:1.20.4-22.amzn2.0.12
Amazon Linux · 2 xorg-x11-server-Xwayland 0:1.20.4-22.amzn2.0.12

Vulnerabilities 9

References

  • web
    https://alas.aws.amazon.com/cve/html/CVE-2026-50256.html
  • web
    https://alas.aws.amazon.com/cve/html/CVE-2026-50257.html
  • web
    https://alas.aws.amazon.com/cve/html/CVE-2026-50258.html
  • web
    https://alas.aws.amazon.com/cve/html/CVE-2026-50259.html
  • web
    https://alas.aws.amazon.com/cve/html/CVE-2026-50260.html
  • web
    https://alas.aws.amazon.com/cve/html/CVE-2026-50261.html
  • web
    https://alas.aws.amazon.com/cve/html/CVE-2026-50262.html
  • web
    https://alas.aws.amazon.com/cve/html/CVE-2026-50263.html
  • web
    https://alas.aws.amazon.com/cve/html/CVE-2026-50264.html