CVE-2026-50259

Medium

Elevated severity or exploit probability.

CVSS base

7.8 HIGH

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS — probability of exploitation (30 days)

0.2%

6.1th percentile

CISA KEV

Not listed

Weakness / dates

CWE-121

Published 2026-06-05 · modified 2026-08-05

CVSS breakdown

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Attack Vector	L	Local
Attack Complexity	L	Low
Privileges Required	L	Low
User Interaction	N	None
Scope	U	Unchanged
Confidentiality	H	High
Integrity	H	High
Availability	H	High

Timeline

2026-06-05 — Published (NVD)
2026-08-05 — Last modified (NVD)

Description

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.

Affected

redhat x.org

References

Official: NVD · CVE.org