RUSTSEC-2021-0055

NULL pointer deref in signature_algorithms processing

Reported

May 1, 2021

Issued

May 1, 2021 (last modified: June 13, 2023)

Package

openssl-src (crates.io)

Type

Vulnerability

Categories

denial-of-service

Aliases

References

https://www.openssl.org/news/secadv/20210325.txt

CVSS Score

5.9 MEDIUM

CVSS Details

Attack vector: Network
Attack complexity: High
Privileges required: None
User interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: None
Availability: High

CVSS Vector

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

Patched

>=111.15

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.

Advisory available under CC0-1.0 license.