CVE-2019-1547 ECDSA remote timing attack

Medium 4.7 Published 10 Sep 2019 Updated 16 Sep 2024

Attackers can recover ECDSA private keys via timing attacks when applications use explicit curve parameters without cofactors in OpenSSL.

Exploited in the wild: Not known
Login needed: Any signed-in user
Attackable: Local or same network only
Victim action needed: Not needed
Fix: Available

What is CVE-2019-1547?

CVE-2019-1547 is a medium-severity vulnerability in Openssl Openssl, published on 10 Sep 2019. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

Normally in OpenSSL EC groups always have a co-factor present and this is used in side channel resistant code paths. However, in some cases, it is possible to construct a group using explicit parameters (instead of using a named curve). In those cases it is possible that such a group does not have the cofactor present. This can occur even where all the parameters match a known named curve. If such a curve is used then OpenSSL falls back to non-side channel resistant code paths which may result in full key recovery during an ECDSA signature operation. In order to be vulnerable an attacker would have to have the ability to time the creation of a large number of signatures where explicit parameters with no co-factor present are in use by an application using libcrypto. For the avoidance of doubt libssl is not vulnerable because explicit parameters are never used. Fixed in OpenSSL 1.1.1d (Affected 1.1.1-1.1.1c). Fixed in OpenSSL 1.1.0l (Affected 1.1.0-1.1.0k). Fixed in OpenSSL 1.0.2t (Affected 1.0.2-1.0.2s).

Which versions are affected by CVE-2019-1547?

It affects 1 product.

Products include Openssl Openssl.

How do I fix CVE-2019-1547?

Upgrade to a fixed version.

Is CVE-2019-1547 being exploited?

There is no known exploitation of CVE-2019-1547 in the wild and no public exploit code.

All Openssl Openssl vulnerabilities

Sources

Also known as ALPINE-CVE-2019-1547, CLEANSTART-2026-TP50755, DEBIAN-CVE-2019-1547, GHSA-q2qv-648h-wcqp, JLSEC-2026-214, UBUNTU-CVE-2019-1547.