CVE-2020-28042

Public Exploit

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.

Category

5.3
CVSS
Severity: Medium
CVSS 3.1 •
CVSS 2.0 •
EPSS 9.25% Top 10%
Vendor Advisory servicestack.net
Affected: n/a n/a
Published at:
Updated at:

References

Link Tags
https://forums.servicestack.net/t/servicestack-v5-9-2-released/8850 release notes vendor advisory
https://github.com/ServiceStack/ServiceStack/commit/540d4060e877a03ae95343c1a8560a26768585ee third party advisory patch
https://www.shielder.it/blog/2020/11/re-discovering-a-jwt-authentication-bypass-in-servicestack/ third party advisory exploit
https://www.shielder.it/advisories/servicestack-jwt-signature-verification-bypass/ third party advisory exploit

Frequently Asked Questions

What is the severity of CVE-2020-28042?
CVE-2020-28042 has been scored as a medium severity vulnerability.
How to fix CVE-2020-28042?
To fix CVE-2020-28042, make sure you are using an up-to-date version of the affected component(s) by checking the vendor release notes. As for now, there are no other specific guidelines available.
Is CVE-2020-28042 being actively exploited in the wild?
It is possible that CVE-2020-28042 is being exploited or will be exploited in a near future based on public information. According to its EPSS score, there is a ~9% probability that this vulnerability will be exploited by malicious actors in the next 30 days.
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