CVE-2021-45105
High
High exploit probability or critical severity with a known exploit.
CVSS base
5.9
MEDIUM
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS — probability of exploitation (30 days)
100.0%
100.0th percentile
CISA KEV
Not listed
Weakness / dates
CWE-20
Published 2021-12-18 · modified 2026-08-25
CVSS breakdown
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
| Attack Vector | N | Network |
| Attack Complexity | H | High |
| Privileges Required | N | None |
| User Interaction | N | None |
| Scope | U | Unchanged |
| Confidentiality | N | None |
| Integrity | N | None |
| Availability | H | High |
Timeline
- 2021-12-18 — Published (NVD)
- 2026-08-25 — Last modified (NVD)
Description
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.
Affected
References
- http://www.openwall.com/lists/oss-security/2021/12/19/1
- https://cert-portal.siemens.com/productcert/pdf/ssa-479842.pdf
- https://cert-portal.siemens.com/productcert/pdf/ssa-501673.pdf
- https://logging.apache.org/log4j/2.x/security.html
- https://psirt.global.sonicwall.com/vuln-detail/SNWLID-2021-0032
- https://security.netapp.com/advisory/ntap-20211218-0001/
- https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-apache-log4j-qRuKNEbd
- https://www.debian.org/security/2021/dsa-5024
- https://www.kb.cert.org/vuls/id/930724
- https://www.oracle.com/security-alerts/cpuapr2022.html
- https://www.oracle.com/security-alerts/cpujan2022.html
- https://www.oracle.com/security-alerts/cpujul2022.html
- https://www.zerodayinitiative.com/advisories/ZDI-21-1541/
- http://www.openwall.com/lists/oss-security/2021/12/19/1
- https://cert-portal.siemens.com/productcert/pdf/ssa-479842.pdf
- https://cert-portal.siemens.com/productcert/pdf/ssa-501673.pdf
- https://logging.apache.org/log4j/2.x/security.html
- https://psirt.global.sonicwall.com/vuln-detail/SNWLID-2021-0032
- https://security.netapp.com/advisory/ntap-20211218-0001/
- https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-apache-log4j-qRuKNEbd
- https://www.debian.org/security/2021/dsa-5024
- https://www.kb.cert.org/vuls/id/930724
- https://www.oracle.com/security-alerts/cpuapr2022.html
- https://www.oracle.com/security-alerts/cpujan2022.html
- https://www.oracle.com/security-alerts/cpujul2022.html
- https://www.zerodayinitiative.com/advisories/ZDI-21-1541/