New in the SumatraPDF [pre-release builds](https://www.sumatrapdfreader.org/prerelease):

## Open PDFs inside .p7m files

SumatraPDF opens PDF documents wrapped in digitally signed `.p7m` files ([#5618](https://github.com/sumatrapdfreader/sumatrapdf/issues/5618)).

More: [changes from May 21, 2026](https://www.sumatrapdfreader.org/docs/Changelog-2026-05-21) and the [full changelog](https://www.sumatrapdfreader.org/docs/Changelog).