CVEs / CVE-2021-45105
CVE-2021-45105: Apache Software Foundation Apache Log4j2 vulnerability
- medium 5.9 CVSS 3.1 (NVD)
- EPSS 99.9% chance of exploitation in the next 30 days, higher than 99% of CVEs (30 Oct 2026)
- Last changed at its sources
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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 and fixed versions
| Product | Affected | Fixed in |
|---|---|---|
| Apache Software Foundation Apache Log4j2 | from log4j-core, before 2.17.0 | 2.17.0 |
| Product | Affected | Fixed in |
|---|---|---|
| org.apache.logging.log4j:log4j-core (Maven) | from 2.4.0, before 2.12.3 | 2.12.3 |
| org.apache.logging.log4j:log4j-core (Maven) | from 2.13.0, before 2.17.0 | 2.17.0 |
| org.apache.logging.log4j:log4j-core (Maven) | before 2.3.1 | 2.3.1 |
| org.ops4j.pax.logging:pax-logging-log4j2 (Maven) | from 1.8.0, before 1.9.2 | 1.9.2 |
| org.ops4j.pax.logging:pax-logging-log4j2 (Maven) | from 1.10.0, before 1.10.9 | 1.10.9 |
| org.ops4j.pax.logging:pax-logging-log4j2 (Maven) | from 1.11.0, before 1.11.12 | 1.11.12 |
| org.ops4j.pax.logging:pax-logging-log4j2 (Maven) | from 2.0.0, before 2.0.13 | 2.0.13 |
Package versions from GHSA-p6xc-xr62-6r2g.
Exploitation
Not in the CISA Known Exploited Vulnerabilities catalog as of 30 Oct 2026.
Severity
| CVSS 3.1 | 5.9 mediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:HScored by NVD |
|---|---|
| Weakness | CWE-20, CWE-674 |
References
- CVE-2021-45105 on NVD
- CVE-2021-45105 on OSV
- http://www.openwall.com/lists/oss-security/2021/12/19/1 Mailing List, Mitigation, Third Party Advisory
- https://cert-portal.siemens.com/productcert/pdf/ssa-479842.pdf Third Party Advisory
- https://cert-portal.siemens.com/productcert/pdf/ssa-501673.pdf Third Party Advisory
- https://logging.apache.org/log4j/2.x/security.html Release Notes, Vendor Advisory
- https://psirt.global.sonicwall.com/vuln-detail/SNWLID-2021-0032 Third Party Advisory
- https://security.netapp.com/advisory/ntap-20211218-0001/ Third Party Advisory
- https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-apache-log4j-qRuKNEbd Third Party Advisory
- https://www.debian.org/security/2021/dsa-5024 Third Party Advisory
- https://www.kb.cert.org/vuls/id/930724 Third Party Advisory, US Government Resource
- https://www.oracle.com/security-alerts/cpuapr2022.html Patch, Third Party Advisory
- https://www.oracle.com/security-alerts/cpujan2022.html Patch, Third Party Advisory
- https://www.oracle.com/security-alerts/cpujul2022.html Third Party Advisory
- https://www.zerodayinitiative.com/advisories/ZDI-21-1541/ Third Party Advisory, VDB Entry
Sources
Exploitation status from the CISA Known Exploited Vulnerabilities catalog. EPSS scores from FIRST. Descriptions, severity and references from the National Vulnerability Database. Open-source package versions from OSV (CC-BY 4.0). Text is shown as each source states it; Stackurity does not edit it. Check the vendor's advisory before acting.
This product uses data from the NVD API but is not endorsed or certified by the NVD.