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.
{
"cna_assigner": "redhat",
"cwe_ids": [
"CWE-121"
],
"osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/50xxx/CVE-2026-50259.json"
}{
"cpe": [
"cpe:2.3:a:x.org:x_server:*:*:*:*:*:*:*:*",
"cpe:2.3:a:x.org:xwayland:*:*:*:*:*:*:*:*",
"cpe:2.3:o:redhat:enterprise_linux:7.0:*:*:*:*:*:*:*"
],
"source": [
"CPE_RANGE",
"CPE_STRING",
"REFERENCES"
],
"extracted_events": [
{
"introduced": "0"
},
{
"fixed": "21.1.23"
},
{
"fixed": "24.1.12"
},
{
"last_affected": "7.0"
}
]
}