Apache Log4j2 versions 2.0-alpha1 through 2.16.0 (excluding 2.12.3 and 2.3.1) did not protect from uncontrolled recursion from self-referential lookups. This allows an attacker with control over Thread Context Map data to cause a denial of service when a crafted string is interpreted. This issue was fixed in Log4j 2.17.0, 2.12.3, and 2.3.1.
https://logging.apache.org/log4j/2.x/security.html
https://security.netapp.com/advisory/ntap-20211218-0001/
http://www.openwall.com/lists/oss-security/2021/12/19/1
https://www.debian.org/security/2021/dsa-5024
https://www.zerodayinitiative.com/advisories/ZDI-21-1541/
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-apache-log4j-qRuKNEbd
https://cert-portal.siemens.com/productcert/pdf/ssa-501673.pdf
https://www.kb.cert.org/vuls/id/930724
https://psirt.global.sonicwall.com/vuln-detail/SNWLID-2021-0032
https://cert-portal.siemens.com/productcert/pdf/ssa-479842.pdf
https://www.oracle.com/security-alerts/cpujan2022.html
Source: MITRE
Published: 2021-12-18
Updated: 2022-10-06
Type: CWE-20
Base Score: 4.3
Vector: AV:N/AC:M/Au:N/C:N/I:N/A:P
Impact Score: 2.9
Exploitability Score: 8.6
Severity: MEDIUM
Base Score: 5.9
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Impact Score: 3.6
Exploitability Score: 2.2
Severity: MEDIUM