CVE-2026-50256: redhat enterprise_linux Stack-based Buffer Overflow

Vulnerability summary

CVE-2026-50256 is a high (CVSS 7.8) Stack-based Buffer Overflow vulnerability in redhat enterprise_linux. EPSS estimates a 0.21% chance of exploitation in the next 30 days, higher than 10.6% of scored vulnerabilities.

Timeline

1. 05-06-2026
   PublishedVulnerability first disclosed.
2. 28-09-2026
   Last modifiedVulnerability information updated.

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.

• CWE-121Stack-based Buffer OverflowA stack-based buffer overflow condition is a condition where the buffer being overwritten is allocated on the stack (i.e., is a local variable or, rarely, a parameter to a function).