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# NSS 3.16.2.3 release notes

## [Introduction](#introduction)

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Network Security Services (NSS) 3.16.2.3 is a patch release for NSS 3.16. The bug fixes in NSS
3.16.2.3 are described in the "Bugs Fixed" section below.
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## [Distribution Information](#distribution_information)

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The HG tag is NSS_3_16_2_3_RTM. NSS 3.16.2.3 requires NSPR 4.10.6 or newer.

NSS 3.16.2.3 source distributions are available on ftp.mozilla.org for secure HTTPS download:

- Source tarballs:
  <https://ftp.mozilla.org/pub/mozilla.org/security/nss/releases/NSS_3_16_2_3_RTM/src/>
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## [New in NSS 3.16.2.3](#new_in_nss_3.16.2.3)

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This patch release fixes a bug and contains a backport of the TLS_FALLBACK_SCSV feature, which
was originally made available in NSS 3.17.1.
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### [New Functionality](#new_functionality)

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- [TLS_FALLBACK_SCSV](https://datatracker.ietf.org/doc/html/draft-ietf-tls-downgrade-scsv-00)
  is a signaling cipher suite value that indicates a handshake is the result of TLS version
  fallback.
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### [New Macros](#new_macros)

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- *in ssl.h*

  - **SSL_ENABLE_FALLBACK_SCSV** - an SSL socket option that enables TLS_FALLBACK_SCSV. Off by
    default.

- *in sslerr.h*

  - **SSL_ERROR_INAPPROPRIATE_FALLBACK_ALERT** - a new SSL error code.

- *in sslproto.h*

  - **TLS_FALLBACK_SCSV** - a signaling cipher suite value that indicates a handshake is the
    result of TLS version fallback.
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## [Notable Changes in NSS 3.16.2.3](#notable_changes_in_nss_3.16.2.3)

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- [Bug 1057161](https://bugzilla.mozilla.org/show_bug.cgi?id=1057161): Check that an imported
  elliptic curve public key is valid. Previously NSS would only validate the peer's public key
  before performing ECDH key agreement. Now EC public keys are validated at import time.
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## [Bugs fixed in NSS 3.16.2.3](#bugs_fixed_in_nss_3.16.2.3)

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- [Bug 1057161](https://bugzilla.mozilla.org/show_bug.cgi?id=1057161) - NSS hangs with 100%
  CPU on invalid EC key
- [Bug 1036735](https://bugzilla.mozilla.org/show_bug.cgi?id=1036735) - Add support for
  draft-ietf-tls-downgrade-scsv to NSS
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## [Compatibility](#compatibility)

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NSS 3.16.2.3 shared libraries are backward compatible with all older NSS 3.x shared libraries. A
program linked with older NSS 3.x shared libraries will work with NSS 3.16.2.3 shared libraries
without recompiling or relinking. Furthermore, applications that restrict their use of NSS APIs
to the functions listed in NSS Public Functions will remain compatible with future versions of
the NSS shared libraries.
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## [Feedback](#feedback)

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Bugs discovered should be reported by filing a bug report with
[bugzilla.mozilla.org](https://bugzilla.mozilla.org/enter_bug.cgi?product=NSS) (product NSS).
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