CVE-2026-50256

Summary

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.

Affected Software

VendorProductVersion RangeStatus
Red HatRed Hat Enterprise Linux 100:24.1.9-4.el10_2.2 < *unaffected
Red HatRed Hat Enterprise Linux 80:21.1.3-20.el8_10.2 < *unaffected
Red HatRed Hat Enterprise Linux 80:1.20.11-28.el8_10.2 < *unaffected
Red HatRed Hat Enterprise Linux 80:1.15.0-10.el8_10 < *unaffected
Red HatRed Hat Enterprise Linux 90:24.1.9-4.el9_8.2 < *unaffected
Red HatRed Hat Enterprise Linux 90:1.20.11-34.el9_8.2 < *unaffected
Red HatRed Hat Enterprise Linux 90:1.15.0-7.el9_8.2 < *unaffected

Weaknesses

  • CWE-121: Stack-based Buffer Overflow

ADP Enrichment

CISA ADP Vulnrichment

  • SSVC:
  • Exploitation: none
    • Automatable: no
    • Technical Impact: total

xorg-x11-server: xorg-x11-server-Xwayland: xorg-x11-server: stack buffer overflow in font alias resolution due to libXfont2 name length mismatch

Additional References

References