I've prepared a new bug-fix release of Nettle, a low-level cryptographics library, to fix bugs in the RSA decryption functions. The bugs cause crashes on certain invalid inputs, which could be used for denial of service attacks on applications using these functions. More details in NEWS file below.

Upgrading is strongly recommended.

The Nettle home page can be found at https://www.lysator.liu.se/~nisse/nettle/, and the manual at https://www.lysator.liu.se/~nisse/nettle/nettle.html.

The release can be downloaded from

https://ftp.gnu.org/gnu/nettle/nettle-3.7.3.tar.gz ftp://ftp.gnu.org/gnu/nettle/nettle-3.7.3.tar.gz https://www.lysator.liu.se/~nisse/archive/nettle-3.7.3.tar.gz

Regards, /Niels

NEWS for the Nettle 3.7.3 release

This is bugfix release, fixing bugs that could make the RSA decryption functions crash on invalid inputs.

Upgrading to the new version is strongly recommended. For applications that want to support older versions of Nettle, the bug can be worked around by adding a check that the RSA ciphertext is in the range 0 < ciphertext < n, before attempting to decrypt it.

Thanks to Paul Schaub and Justus Winter for reporting these problems.

The new version is intended to be fully source and binary compatible with Nettle-3.6. The shared library names are libnettle.so.8.4 and libhogweed.so.6.4, with sonames libnettle.so.8 and libhogweed.so.6.

Bug fixes:

* Fix crash for zero input to rsa_sec_decrypt and rsa_decrypt_tr. Potential denial of service vector.

* Ensure that all of rsa_decrypt_tr and rsa_sec_decrypt return failure for out of range inputs, instead of either crashing, or silently reducing input modulo n. Potential denial of service vector.

* Ensure that rsa_decrypt returns failure for out of range inputs, instead of silently reducing input modulo n.

* Ensure that rsa_sec_decrypt returns failure if the message size is too large for the given key. Unlike the other bugs, this would typically be triggered by invalid local configuration, rather than by processing untrusted remote data.