CVE-2021-3449

Description

An OpenSSL TLS server may crash if sent a maliciously crafted renegotiation ClientHello message from a client. If a TLSv1.2 renegotiation ClientHello omits the signature_algorithms extension (where it was present in the initial ClientHello), but includes a signature_algorithms_cert extension then a NULL pointer dereference will result, leading to a crash and a denial of service attack. A server is only vulnerable if it has TLSv1.2 and renegotiation enabled (which is the default configuration). OpenSSL TLS clients are not impacted by this issue. All OpenSSL 1.1.1 versions are affected by this issue. Users of these versions should upgrade to OpenSSL 1.1.1k. OpenSSL 1.0.2 is not impacted by this issue. Fixed in OpenSSL 1.1.1k (Affected 1.1.1-1.1.1j).

How to fix CVE-2021-3449

To remediate CVE-2021-3449, upgrade the affected package to a fixed version below.

—upgrade to 1.1.1k-r0 or later
—upgrade to 1.1.1k-r0 or later
—upgrade to 10.12.1 or later
—upgrade to 10.12.1 or later
—upgrade to 111.15.0 or later
—upgrade to 111.15.0 or later
—upgrade to 1.1.1d-0+deb10u6 or later
—upgrade to 1.1.1k-1 or later

Is CVE-2021-3449 being exploited?

Moderate — EPSS is 9.9%. Track this CVE but it's not at the top of the prioritisation list.

Affected packages (8)

from 0, < 1.1.1k-r0
from 0, < 1.1.1k-r0
>= 10.0.0, < 10.12.1, >= 10.13.0, < 10.24.1, >= 12.0.0, < 12.12.1, >= 12.13.0, < 12.22.1, >= 14.0.0, < 14.14.1, >= 14.15.0, < 14.16.1, >= 15.0.0, < 15.14.0
>= 10.0.0, < 10.12.1, >= 10.13.0, < 10.24.1, >= 12.0.0, < 12.12.1, >= 12.13.0, < 12.22.1, >= 14.0.0, < 14.14.1, >= 14.15.0, < 14.16.1, >= 15.0.0, < 15.14.0
>= 0.0.0-0, < 111.15.0
from 0, < 111.15.0
from 0, < 1.1.1d-0+deb10u6
from 0, < 1.1.1k-1

CVSS scores

Source	Version	Severity	Vector
osv	CVSS 3.1	MEDIUM5.9	CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H