Subject: [ASA-202103-1] gnutls: arbitrary code execution

Arch Linux Security Advisory ASA-202103-1
=========================================

Severity: Low
Date    : 2021-03-13
CVE-ID  : CVE-2021-20231 CVE-2021-20232
Package : gnutls
Type    : arbitrary code execution
Remote  : Yes
Link    : https://security.archlinux.org/AVG-1674

Summary
=======

The package gnutls before version 3.7.1-1 is vulnerable to arbitrary
code execution.

Resolution
==========

Upgrade to 3.7.1-1.

# pacman -Syu "gnutls>=3.7.1-1"

The problems have been fixed upstream in version 3.7.1.

Workaround
==========

None.

Description
===========

- CVE-2021-20231 (arbitrary code execution)

A security issue was found in GnuTLS before version 3.7.1. It was found
that the client sending a "key_share" extension may result in
dereferencing a pointer no longer valid after realloc(). This only
happens in TLS 1.3 and only when the client sends a large Client Hello
message, e.g., when HRR is sent in a resumed session previously
negotiated large FFDHE parameters, because the initial allocation of
the buffer is large enough without having to call realloc().

- CVE-2021-20232 (arbitrary code execution)

A security issue was found in GnuTLS before version 3.7.1. It was found
that the client sending a "pre_share_key" extension may result in
dereferencing a pointer no longer valid after realloc(). This only
happens in TLS 1.3 and only when the client sends a large Client Hello
message, e.g., when HRR is sent in a resumed session previously
negotiated large FFDHE parameters, because the initial allocation of
the buffer is large enough without having to call realloc().

Impact
======

A remote attacker might be able to cause a denial of service or
possibly execute arbitrary code when a TLS client is resuming a TLS 1.3
session.

References
==========

https://www.gnutls.org/security-new.html#GNUTLS-SA-2021-03-10
https://gitlab.com/gnutls/gnutls/-/issues/1151
https://gitlab.com/gnutls/gnutls/-/merge_requests/1399
https://gitlab.com/gnutls/gnutls/-/commit/15beb4b193b2714d88107e7dffca781798684e7e
https://gitlab.com/gnutls/gnutls/-/commit/75a937d97f4fefc6f9b08e3791f151445f551cb3
https://security.archlinux.org/CVE-2021-20231
https://security.archlinux.org/CVE-2021-20232