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AUSCERT External Security Bulletin Redistribution
USN-4738-1: OpenSSL vulnerabilities
19 February 2021
AusCERT Security Bulletin Summary
Operating System: Ubuntu
Impact/Access: Denial of Service -- Remote/Unauthenticated
Reduced Security -- Remote/Unauthenticated
CVE Names: CVE-2021-23841 CVE-2021-23840
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TITLE: USN-4738-1: OpenSSL vulnerabilities
Found CVEs: CVE-2021-23840 CVE-2021-23841
USN-4738-1: OpenSSL vulnerabilities
18 February 2021
Several security issues were fixed in OpenSSL.
o Ubuntu 20.10
o Ubuntu 20.04 LTS
o Ubuntu 18.04 LTS
o Ubuntu 16.04 LTS
o openssl - Secure Socket Layer (SSL) cryptographic library and tools
o openssl1.0 - Secure Socket Layer (SSL) cryptographic library and tools
Paul Kehrer discovered that OpenSSL incorrectly handled certain input
lengths in EVP functions. A remote attacker could possibly use this issue
to cause OpenSSL to crash, resulting in a denial of service.
( CVE-2021-23840 )
Tavis Ormandy discovered that OpenSSL incorrectly handled parsing issuer
fields. A remote attacker could possibly use this issue to cause OpenSSL to
crash, resulting in a denial of service. ( CVE-2021-23841 )
The problem can be corrected by updating your system to the following package
o libssl1.1 - 1.1.1f-1ubuntu4.2
o libssl1.1 - 1.1.1f-1ubuntu2.2
o libssl1.0.0 - 1.0.2n-1ubuntu5.6
o libssl1.1 - 1.1.1-1ubuntu2.1~18.04.8
o libssl1.0.0 - 1.0.2g-1ubuntu4.19
After a standard system update you need to reboot your computer to make
all the necessary changes.
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