CVE-2026-86469

A flaw was found in GLib2. When g_file_replace() is used with G_FILE_CREATE_REPLACE_DESTINATION and creating the .goutputstream-XXXXXX temporary file fails, the library unlinks the destination and recreates it without exclusive creation or symlink protection. A local attacker who can write to the destination directory can win that race and redirect the write to another file.

Exploitation is local, requires write access to the destination directory, requires the uncommon temp-file fallback in handle_overwrite_open(), and requires winning a race. The usual g_file_replace() path writes to a temp file first and is not this bug. A successful race can overwrite or create a file the victim process is allowed to write.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Do not use g_file_replace(..., G_FILE_CREATE_REPLACE_DESTINATION) on paths in directories writable by less-privileged users.