There's two fundamentally different takes on open source licenses:

a) the permissive ones like MIT, Apache etc which - roughly speaking - don't care what happens to their sources as long as the credits are maintained and communicated.

b) And there's the more strictly open source licenses, the copy-left licenses, which want to make sure that any derivative remains also open source, most notably the GPL license.

The license is usually chosen by the (initial) authors for a reason that s/he wants the first or the latter.

As such a license as you seek might be crafted, but serves little use: A permissively-licensed project would not want to make use of a license which can only be used in open-source projects; its license was chosen particularily such that proprietary use is possible.

A project already with a copy-left license does not need such license either - it could as well use the GPL which ensures just that: be open source and stay open source.

As such, it might even be argued that a license which may be used only in an open source project already exists: the GPL. Most open source licenses are compatible with the GPL in the sense that they may be used in a GPL-licensed project (by simply changing the license to GPL for the derived / combined software - even when notable exceptions exist like the incompatibility with Apache or MPL).

There are two fundamentally different takes on open-source licenses:

1. the permissive ones like MIT, Apache etc which - roughly speaking - don't care what happens to their sources as long as the credits are maintained and communicated.

2. And there are the more strictly open source licenses, the copy-left licenses, which want to make sure that any derivative remains also open source, most notably the GPL license.

The license is usually chosen by the (initial) authors for a reason that s/he wants the first or the latter.

As such a license as you seek might be crafted, but serves little use: A permissively-licensed project would not want to make use of a license that can only be used in open-source projects; its license was chosen particularly such that proprietary use is possible.

A project already with a copy-left license does not need such a license either - it could as well use the GPL which ensures just that: be open source and stay open source.

As such, it might even be argued that a license that may be used only in an open-source project already exists: the GPL. Most open source licenses are compatible with the GPL in the sense that they may be used in a GPL-licensed project (by simply changing the license to GPL for the derived / combined software - even when notable exceptions exist like the incompatibility with Apache or MPL).