Infinite recursion in Apache Log4j
| Risk | Medium |
| Patch available | YES |
| Number of vulnerabilities | 1 |
| CVE-ID | CVE-2021-45105 |
| CWE-ID | CWE-835 |
| Exploitation vector | Network |
| Public exploit | Public exploit code for vulnerability #1 is available. |
| Vulnerable software Subscribe |
Apache Log4j Universal components / Libraries / Libraries used by multiple products |
| Vendor | Apache Foundation |
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: No
DescriptionThe 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}}}}
MitigationInstall updates from vendor's website.
Vulnerable software versionsApache Log4j: 2.8 - 2.16.0
External linkshttp://issues.apache.org/jira/browse/LOG4J2-3230
http://logging.apache.org/log4j/2.x/security.html
http://www.zerodayinitiative.com/advisories/ZDI-21-1541/
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.
