Denial of service in Red Hat Single Sign-On 7.5 on RHEL 7

Published: 2022-04-21
Risk Medium
Patch available YES
Number of vulnerabilities 1
CVE-ID CVE-2021-45105
Exploitation vector Network
Public exploit Public exploit code for vulnerability #1 is available.
Vulnerable software
rh-sso7-keycloak (Red Hat package)
Operating systems & Components / Operating system package or component

Red Hat Single Sign-On
Server applications / Directory software, identity management

Vendor Red Hat Inc.

Security Bulletin

This security bulletin contains one medium risk vulnerability.

1) Infinite loop

EUVDB-ID: #VU59051

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-2021-45105

CWE-ID: CWE-835 - Loop with Unreachable Exit Condition ('Infinite Loop')

Exploit availability: Yes


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

The vulnerability exists due to infinite loop within the StrSubstitutor class. A remote attacker can pass specially crafted input to the application, consume all available system resources and cause denial of service conditions.

Payload example: ${${::-${::-$${::-j}}}}


Install updates from vendor's website.

Vulnerable software versions

rh-sso7-keycloak (Red Hat package): 15.0.4-1.redhat_00003.1.el7sso

Red Hat Single Sign-On: 7.5.0 - 7.5.1

CPE2.3 External links

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.