Vulnerability identifier: #VU55665

Vulnerability risk: Medium

CVSSv3.1: 6.7 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:P/RL:O/RC:C]

CVE-ID: CVE-2021-34558

CWE-ID: CWE-295

Exploitation vector: Network

Exploit availability: Yes

Vulnerable software:
Go programming language
Universal components / Libraries / Scripting languages

Vendor: Google

Description

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

The vulnerability exists due to improper certificate verification in crypto/tls package in Go when processing X.509 certificates. The application does not properly assert that the type of public key in an X.509 certificate matches the expected type when doing a RSA based key exchange, allowing a malicious TLS server to cause a TLS client to panic.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Go programming language: 1.16 - 1.16.5

---

External links
http://groups.google.com/g/golang-announce
http://groups.google.com/g/golang-announce/c/n9FxMelZGAQ
http://golang.org/doc/devel/release#go1.16.minor
http://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/3BA7MFVXRBEKRTLSLYDICTYCGEMK2HZ7/
http://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/D7FRFM7WWR2JCT6NORQ7AO6B453OMI3I/
http://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/WXJ2MVMAHOIGRH37ZSFYC4EVWLJFL2EQ/
http://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/JYIUSR4YP52PWG7YE7AA3DZ5OSURNFJB/

---

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.