[ASA-202003-4] golang-golang-x-crypto: denial of service

[Morten Linderud]

Arch Linux Security Advisory ASA-202003-4
=========================================

Severity: Medium
Date    : 2020-03-08
CVE-ID  : CVE-2020-9283
Package : golang-golang-x-crypto
Type    : denial of service
Remote  : Yes
Link    : https://security.archlinux.org/AVG-1109

Summary
=======

The package golang-golang-x-crypto before version 0.0.20200303-1 is
vulnerable to denial of service.

Resolution
==========

Upgrade to 0.0.20200303-1.

# pacman -Syu "golang-golang-x-crypto>=0.0.20200303-1"

The problem has been fixed upstream in version 0.0.20200303.

Workaround
==========

None.

Description
===========

A security issue has been found in golang.org/x/crypto before
v0.0.0-20200220183623-bac4c82f6975. An attacker can craft an ssh-
ed25519 or sk-ssh-ed25519 at openssh.com public key, such that the library
will panic when trying to verify a signature with it. Clients can
deliver such a public key and signature to any golang.org/x/crypto/ssh
server with a PublicKeyCallback, and servers can deliver them to any
golang.org/x/crypto/ssh client.

Impact
======

A remote unauthenticated attacker can serve a malicious SSH public key
and crash the service.

References
==========

https://groups.google.com/forum/#!topic/golang-announce/3L45YRc91SY
https://github.com/golang/crypto/commit/bac4c82f69751a6dd76e702d54b3ceb88adab236
https://packetstormsecurity.com/files/156480/Go-SSH-0.0.2-Denial-Of-Service.html
https://security.archlinux.org/CVE-2020-9283
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