Two high-severity vulnerabilities in OpenSSL

[Miroslav Lachman]

The OpenSSL Project on Thursday 2021-03-25 announced the release of 
version 1.1.1k, which patches two high-severity vulnerabilities, 
including one related to verifying a certificate chain and one that can 
lead to a server crash.

https://www.securityweek.com/openssl-111k-patches-two-high-severity-vulnerabilities

The first security hole, tracked as CVE-2021-3450, has been described as 
a “problem with verifying a certificate chain when using the 
X509_V_FLAG_X509_STRICT flag.” The flaw was discovered by researchers at 
Akamai.

“Starting from OpenSSL version 1.1.1h a check to disallow certificates 
in the chain that have explicitly encoded elliptic curve parameters was 
added as an additional strict check. An error in the implementation of 
this check meant that the result of a previous check to confirm that 
certificates in the chain are valid CA certificates was overwritten. 
This effectively bypasses the check that non-CA certificates must not be 
able to issue other certificates,” the OpenSSL Project explained in its 
advisory.

The second vulnerability, tracked as CVE-2021-3449 and discovered by 
employees of telecoms giant Nokia, involves sending a specially crafted 
renegotiation ClientHello message from a client, and it can be exploited 
for denial-of-service (DoS) attacks.

“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,” reads the description of this vulnerability.

Servers running OpenSSL 1.1.1 are affected by CVE-2021-3449 if they have 
TLS 1.2 and renegotiation enabled — this is the default configuration.

Some companies have already started informing their customers about 
these OpenSSL vulnerabilities.


https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-3449

https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-3450

https://www.openssl.org/news/vulnerabilities.html

Kind regards
Miroslav Lachman