OpenSSL Project released 1.1.1k version to fix two High-severity flaws

The OpenSSL Project addresses two high-severity vulnerabilities, including one related to verifying a certificate chain and one that can trigger a DoS condition.

The OpenSSL Project this week released version 1.1.1k to address two high-severity vulnerabilities, respectively tracked as CVE-2021-3450 and CVE-2021-3449.

The CVE-2021-3449 vulnerability could be exploited to trigger a DoS condition by sending a specially crafted renegotiation ClientHello message from a client.

“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,” State the advisory.

The issue affects servers running OpenSSL 1.1.1 versions with TLS 1.2 and renegotiation enabled, which is the default configuration. The vulnerability was reported by Peter Kästle and Samuel Sapalski from Nokia.

The CVE-2021-3450 vulnerability is related to the verification of a certificate chain when using the X509_V_FLAG_X509_STRICT flag.

“The X509_V_FLAG_X509_STRICT flag enables additional security checks of the certificates present in a certificate chain. It is not set by default. 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.” reads the advisory published by the OpenSSL Project. “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 vulnerability was reported by Benjamin Kaduk and Xiang Ding from Akamai.

In February 2021, the OpenSSL Project released security patches to address three vulnerabilities, two denial-of-service (DoS) flaws, and an incorrect SSLv2 rollback protection issue.

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Pierluigi Paganini

(SecurityAffairs – hacking, OpenSSL Project)

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Pierluigi Paganini

Pierluigi Paganini is member of the ENISA (European Union Agency for Network and Information Security) Threat Landscape Stakeholder Group and Cyber G7 Group, he is also a Security Evangelist, Security Analyst and Freelance Writer. Editor-in-Chief at "Cyber Defense Magazine", Pierluigi is a cyber security expert with over 20 years experience in the field, he is Certified Ethical Hacker at EC Council in London. The passion for writing and a strong belief that security is founded on sharing and awareness led Pierluigi to find the security blog "Security Affairs" recently named a Top National Security Resource for US. Pierluigi is a member of the "The Hacker News" team and he is a writer for some major publications in the field such as Cyber War Zone, ICTTF, Infosec Island, Infosec Institute, The Hacker News Magazine and for many other Security magazines. Author of the Books "The Deep Dark Web" and “Digital Virtual Currency and Bitcoin”.