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CVE-2021-3449

5.9 · MEDIUM

An OpenSSL TLS server may crash if sent a maliciously crafted renegotiation ClientHello message from a client.

Published Mar 25, 2021CWE-476EPSS 63.54%

Overview

CVE-2021-3449 is a medium-severity vulnerability. It was published on March 25, 2021 and has a CVSS 3.1 base score of 5.9 (MEDIUM).

This vulnerability has a CVSS 3.1 base score of 5.9, rated MEDIUM. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

Technical 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).

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

Refwww.openwall.com/lists/oss-security/2021/03/27/1Refwww.openwall.com/lists/oss-security/2021/03/27/2Refwww.openwall.com/lists/oss-security/2021/03/28/3Refwww.openwall.com/lists/oss-security/2021/03/28/4Refcert-portal.siemens.com/productcert/pdf/ssa-389290.pdfRefcert-portal.siemens.com/productcert/pdf/ssa-772220.pdfRefgit.openssl.org/gitweb/?p=openssl.git%3Ba=commitdiff%3Bh=fb9fa6b51defd48157eeb207f52181f735d96148Refkb.pulsesecure.net/articles/Pulse_Security_Advisories/SA44845Refkc.mcafee.com/corporate/index?page=content&id=SB10356Reflists.debian.org/debian-lts-announce/2021/08/msg00029.html

How CyberStrike helps

Frequently asked questions

What is CVE-2021-3449?

CVE-2021-3449 is a medium-severity vulnerability. It was published on March 25, 2021 and has a CVSS 3.1 base score of 5.9 (MEDIUM).

How severe is CVE-2021-3449?

This vulnerability has a CVSS 3.1 base score of 5.9, rated MEDIUM. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-2021-3449?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2021-3449?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2021-3449 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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