#VU50809 Improper Authentication in jwt-go - CVE-2020-26160

Vulnerability identifier: #VU50809

Vulnerability risk: Medium

CVSSv4.0: 6.6 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2020-26160

CWE-ID: CWE-287

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
jwt-go
Web applications / Other software

Vendor: Dave Grijalva

Description

The vulnerability allows a remote attacker to bypass authentication process.

The vulnerability exists due to improper validation when processing data passed via m["aud"]. A remote attacker can pass the []string{} string, which is allowed by the specification, however treated as an empty string and bypass authentication checks.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

jwt-go: 1.0.0 - 3.2.0

---

External links
https://github.com/dgrijalva/jwt-go/pull/426
https://snyk.io/vuln/SNYK-GOLANG-GITHUBCOMDGRIJALVAJWTGO-596515
https://github.com/dgrijalva/jwt-go/issues/422

---

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.