Vulnerability CVE-2021-3449


Published: 2021-03-25

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).

Type:

CWE-476

(NULL Pointer Dereference)

CVSS2 => (AV:N/AC:M/Au:N/C:N/I:N/A:P)

CVSS Base Score
Impact Subscore
Exploitability Subscore
4.3/10
2.9/10
8.6/10
Exploit range
Attack complexity
Authentication
Remote
Medium
No required
Confidentiality impact
Integrity impact
Availability impact
None
None
Partial
Affected software
Windriver -> Linux 
Openssl -> Openssl 
Freebsd -> Freebsd 
Debian -> Debian linux 

 References:
http://www.openwall.com/lists/oss-security/2021/03/27/1
http://www.openwall.com/lists/oss-security/2021/03/27/2
http://www.openwall.com/lists/oss-security/2021/03/28/3
http://www.openwall.com/lists/oss-security/2021/03/28/4
https://git.openssl.org/gitweb/?p=openssl.git;a=commitdiff;h=fb9fa6b51defd48157eeb207f52181f735d96148
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/CCBFLLVQVILIVGZMBJL3IXZGKWQISYNP/
https://security.FreeBSD.org/advisories/FreeBSD-SA-21:07.openssl.asc
https://security.gentoo.org/glsa/202103-03
https://security.netapp.com/advisory/ntap-20210326-0006/
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-openssl-2021-GHY28dJd
https://www.debian.org/security/2021/dsa-4875
https://www.openssl.org/news/secadv/20210325.txt
https://www.tenable.com/security/tns-2021-05
https://www.tenable.com/security/tns-2021-06

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