ANNOUNCE: Nettle-3.7.3

Niels Möller nisse at
Mon Jun 7 08:59:28 CEST 2021

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, and the manual at

The release can be downloaded from


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

	The new version is intended to be fully source and binary
	compatible with Nettle-3.6. The shared library names are and, with sonames and

	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

Niels Möller. PGP-encrypted email is preferred. Keyid 368C6677.
Internet email is subject to wholesale government surveillance.

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