Arch Linux Security Advisory ASA-201906-7
========================================
Severity: Low
Date    : 2019-06-11
CVE-ID  : CVE-2019-1543
Package : openssl
Type    : information disclosure
Remote  : Yes
Link    : https://security.archlinux.org/AVG-919

Summary
======
The package openssl before version 1.1.1.c-1 is vulnerable to
information disclosure.

Resolution
=========
Upgrade to 1.1.1.c-1.

# pacman -Syu "openssl>=1.1.1.c-1"

The problem has been fixed upstream in version 1.1.1.c.

Workaround
=========
None.

Description
==========
An issue has been found in OpenSSL <= 1.1.1b, where an application
using ChaCha20-Poly1305 could set a non-default nonce length to be
longer than 12 bytes and then mistakenly reuse a nonce.
ChaCha20-Poly1305 is an AEAD cipher, and requires a unique nonce input
for every encryption operation. RFC 7539 specifies that the nonce value
(IV) should be 96 bits (12 bytes). OpenSSL allows a variable nonce
length and front pads the nonce with 0 bytes if it is less than 12
bytes. However it also incorrectly allows a nonce to be set of up to 16
bytes. In this case only the last 12 bytes are significant and any
additional leading bytes are ignored.

Impact
=====
A remote attacker could disclose sensitive information via an invalid
nonce.

References
=========
https://www.openssl.org/news/secadv/20190306.txt
https://github.com/openssl/openssl/commit/f426625b6a
https://security.archlinux.org/CVE-2019-1543