NULL pointer dereference in openssl (Alpine package)

1) NULL pointer dereference

EUVDB-ID: #VU27061

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-2020-1967

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 within the SSL_check_chain() function during or after a TLS 1.3 handshake. A remote attacker can send an invalid or unrecognised signature algorithm and perform a denial of service (DoS) attack.

Mitigation

Install update from vendor's website.

Vulnerable software versions

openssl (Alpine package): 1.1.1d-r0 - 1.1.1f-r0

CPE2.3

• cpe:2.3:a:alpine:openssl_alpine_package:1.1.1d-r0:*:*:*:*:alpine_linux:*:3.9
• cpe:2.3:a:alpine:openssl_alpine_package:1.1.1d-r0-r0:*:*:*:*:alpine_linux:*:3.9
• cpe:2.3:a:alpine:openssl_alpine_package:1.1.1d-r1:*:*:*:*:alpine_linux:*:3.9

External links

https://git.alpinelinux.org/aports/commit/?id=11ace5cb8b9c94ef9fcca23e4b0401d06c7e399c
https://git.alpinelinux.org/aports/commit/?id=9919f140cf7d3ff305dda398a2a2605489202e60
https://git.alpinelinux.org/aports/commit/?id=e54b51b1d389ed731a8bce1f0a24c45820619dbd
https://git.alpinelinux.org/aports/commit/?id=8d308c15ed58152196218b079d66720ad606405a

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.