7.8
High
CVE-2026-50256 Xorg-x11-server: xorg-x11-server-xwayland: xorg-x11-server: stack buffer overflow in font alias resolution due to libxfont2 name length mismatch
Description
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.
CVSS 3.1 detail
Vector CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HExploitable with local access to the machine, with an ordinary account and without any user action; an attacker can seriously compromise confidentiality, integrity or availability.
- Attack vector
- Local
- Attack complexity
- Low
- Privileges required
- Low
- Interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
Affected products and versions
| Product | Affected versions | Fixed in |
|---|---|---|
| Red Hat Enterprise Linux 10 | Versions not published | |
| Red Hat Enterprise Linux 6 | Versions not published | |
| Red Hat Enterprise Linux 7 | Versions not published | |
| Red Hat Enterprise Linux 8 | Versions not published | |
| Red Hat Enterprise Linux 9 | Versions not published | |
| Red Hat Enterprise Linux AppStream (v. 10) | Versions not published | |
| Red Hat Enterprise Linux AppStream (v. 8) | Versions not published | |
| Red Hat Enterprise Linux AppStream (v. 9) | Versions not published | |
| Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) | Versions not published |
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