Envoy impact of OpenSSL security update, March 15, 2022

[Ryan Hamilton]

TL;DR: Mainline Envoy builds use BoringSSL and are NOT affected.  Any custom builds using OpenSSL will have to do their own analysis.

Howdy Folks,

As you may already be aware, OpenSSL have recently published a security update addressing a bug. While Envoy does not use OpenSSL, it does use BoringSSL which is based on OpenSSL. BoringSSL shares the underlying bug in BN_mod_sqrt as OpenSSL, but it is mostly unaffected by the DoS vulnerability. In particular, this bug is not reachable in BoringSSL from certificate and other ASN.1 elliptic curve parsing code. Any impact in BoringSSL is limited to:

• Callers of EC_GROUP_new_curve_GFp that take untrusted curve parameters
• Callers of BN_mod_sqrt that take untrusted moduli

As Envoy does not call either of this methods, it is not affected by the vulnerability.

Cheers,

Ryan (on behalf of Envoy Security Team)