{"cve":"CVE-2026-50256","nvd":{"published":"2026-06-05T12:16:38.727","modified":"2026-08-05T13:23:28.273","status":"Modified","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_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","score":7.8},"cwes":["CWE-121"],"references":["https://access.redhat.com/errata/RHSA-2026:26562","https://access.redhat.com/errata/RHSA-2026:26566","https://access.redhat.com/errata/RHSA-2026:26590","https://access.redhat.com/errata/RHSA-2026:26610","https://access.redhat.com/errata/RHSA-2026:26709"],"products":["redhat:enterprise_linux","x.org:x_server","x.org:xwayland"],"source":"nvd","synced_at":"2026-10-19T22:37:48.043517290+00:00"},"epss":{"cve":"CVE-2026-50256","score":0.00157,"percentile":0.04858,"date":"2026-10-31"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}