CVE-2020-28042 Signature validation bypass in ServiceStack

Medium 5.3 Published 1 Nov 2020 Updated 4 Aug 2024

Attackers can bypass JWT signature verification in ServiceStack, potentially gaining unauthorized access to protected resources.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Over the internet
Victim action needed: Not needed
Fix: Available

What is CVE-2020-28042?

CVE-2020-28042 is a medium-severity authentication bypass vulnerability in n/a, published on 1 Nov 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

ServiceStack before 5.9.2 mishandles JWT signature verification unless an application has a custom ValidateToken function that establishes a valid minimum length for a signature.

Weakness: CWE-347

Which versions are affected by CVE-2020-28042?

2 open source packages ship an affected version, including ServiceStack. It affects 1 product.

Package	Affected	Fixed in
`ServiceStack` NuGet	All versions	`5.9.2`
`ServiceStack` NuGet	All versions	`5.9.2`

Products include Servicestack Servicestack.

How do I fix CVE-2020-28042?

Upgrade ServiceStack to 5.9.2 or later.

Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.

Is CVE-2020-28042 being exploited?

There is no known exploitation of CVE-2020-28042 in the wild and no public exploit code.

Public exploit code: 1 proofs of concept on GitHub.

Sources

Also known as GHSA-v5rv-hpxg-8x49.