CVE•Published 2026-06-05•Modified 2026-06-08•0 articles on news•6 live references•NVD data

CVE-2026-50258X.org · X_server

Vulnerability data via NVD (ingested)

CVSS v3.1

7.8

HIGH

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

EPSS percentile

Exploit Prediction Scoring System · top 98% of all CVEs

Weaknesses (CWE)

CWE-121Stack-based Buffer Overflow

Description

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.

Timeline

Published 2026-06-05

Modified 2026-06-08

External references

NVD MITRE Exploit-DB GitHub PoC Sploitus VulnCheck

Search for exposed instances

Shodan + Censys queries derived from NVD's CPE data. The vuln tag catches assets Shodan has explicitly linked to this CVE; the product / banner fingerprints find exposed instances even when the vuln tag was never applied (which is common).

Shodan · vuln tag0 hosts

vuln:CVE-2026-50258

Hosts Shodan has explicitly fingerprinted as vulnerable.

Shodan · product

product:"X.org X Server"

All exposed X.org X Server instances — cross-reference with the CVE's affected-version range.

Shodan · banner/body mention

http.html:"X Server"

HTTP body or banner mentions "X Server" — catches deploys Shodan didn't identify as a product.

More intel sources (5)

Shodan report

vuln:CVE-2026-50258