Infinite loop in Apache Log4j - CVE-2021-45105

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Main Vulnerability Database Vulnerabilities #VU59051

Infinite loop in Apache Log4j - CVE-2021-45105

Published: December 18, 2021 / Updated: February 9, 2023


Vulnerability identifier: #VU59051
CSH Severity: Medium
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:P/U:Green
CVE-ID: CVE-2021-45105
CWE-ID: CWE-835
Exploitation vector: Remote access
Exploit availability: Public exploit is available
Vendor: Apache Foundation
Affected software:
Apache Log4j

Detailed vulnerability description

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}}}}


How to mitigate CVE-2021-45105

Install updates from vendor's website.

Sources