Ubuntu update for openssl

1) NULL pointer dereference

EUVDB-ID: #VU51733

Risk: Medium

CVSSv4.0: 7.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:P/U:Green]

CVE-ID: CVE-2021-3449

CWE-ID: CWE-476 - NULL Pointer Dereference

Exploit availability: Yes

Description

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due to a NULL pointer dereference error when processing TLSv1.2 renegotiations. A remote attacker can send a maliciously crafted renegotiation ClientHello message, which omits the signature_algorithms extension but includes a signature_algorithms_cert extension, trigger a NULL pointer dereference error and crash the server.

Mitigation

Update the affected package openssl to the latest version.

Vulnerable software versions

Ubuntu: 18.04 - 20.10

libssl1.1 (Ubuntu package): before 1.1.1f-1ubuntu2.3

CPE2.3

• cpe:2.3:o:canonical:ubuntu:18.04:*:*:*:*:*:*:*
• cpe:2.3:o:canonical:ubuntu:20.04:*:*:*:*:*:*:*
• cpe:2.3:o:canonical:ubuntu:20.10:*:*:*:*:*:*:*
• cpe:2.3:a:canonical:libssl1.1_ubuntu_package:*:*:*:*:*:ubuntu:*:*

External links

https://ubuntu.com/security/notices/USN-4891-1

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability. However, proof of concept for this vulnerability is available.