CVE-2021-45105

Exploitation

Assessed, none found. CISA's assessment recorded neither public exploit code nor evidence of exploitation when it was made.

SSVC decision

• ExploitationnoneCISA recorded no public exploit code and no evidence of exploitation.
• AutomatablenoAt least one step from reconnaissance to exploitation cannot be reliably automated.
• Technical ImpactpartialSuccessful exploitation gives limited control of the vulnerable component.

CISA publishes the decision points, not a final SSVC decision. The decision also depends on mission and well-being impact, which is a property of your deployment rather than of the vulnerability.

EPSS probability

99.99% probability of exploitation activity in the next 30 days.

EPSS percentile

Equal to or higher than the score of 99.9% of scored records. A rank, not a probability.

NVD base score

5.9 (CVSS v3.x), scored by the NVD independently of the CNA.

NVD CVSS vector

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

NVD analysis status

Modified. NVD last modified this record on 2026-08-25.

Red Hat severity

Moderate. Red Hat's rating for its own products, not a CVSS rating.

Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.

Published

2021-12-18 11:55Z4 YR AGO

Last updated

2026-05-29 11:45Z5 MO AGO

Reserved

2021-12-16

Assigning CNA

apache

Record state

PUBLISHED

Severity

Medium (CVSS 5.9)

CNA CVSS vector

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

Weaknesses

• CWE-20Improper Input ValidationClass
• CWE-674Uncontrolled RecursionClass
• CWE-835Loop with Unreachable Exit Condition ('Infinite Loop')Base

Data version

5.2

Document digest

ece7690bfb7b53accb82e2c4ccee1c555b3b11c50467ee069f688cfb394c4bb1

• logging.apache.orghttps://logging.apache.org/log4j/2.x/security.htmlx_refsource_MISC
• psirt.global.sonicwall.comhttps://psirt.global.sonicwall.com/vuln-detail/SNWLID-2021-0032x_refsource_CONFIRM
• www.kb.cert.orgVU#930724https://www.kb.cert.org/vuls/id/930724third-party-advisoryx_refsource_CERT-VN
• tools.cisco.com20211210 Vulnerabilities in Apache Log4j Library Affecting Cisco Products: December 2021https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-apache-log4j-qRuKNEbdvendor-advisoryx_refsource_CISCO
• www.openwall.com[oss-security] 20211218 CVE-2021-45105: Apache Log4j2 does not always protect from infinite recursion in lookup evaluationhttp://www.openwall.com/lists/oss-security/2021/12/19/1mailing-listx_refsource_MLIST
• www.debian.orgDSA-5024https://www.debian.org/security/2021/dsa-5024vendor-advisoryx_refsource_DEBIAN
• cert-portal.siemens.comhttps://cert-portal.siemens.com/productcert/pdf/ssa-479842.pdfx_refsource_CONFIRM
• security.netapp.comhttps://security.netapp.com/advisory/ntap-20211218-0001/x_refsource_CONFIRM
• www.zerodayinitiative.comhttps://www.zerodayinitiative.com/advisories/ZDI-21-1541/x_refsource_MISC
• cert-portal.siemens.comhttps://cert-portal.siemens.com/productcert/pdf/ssa-501673.pdfx_refsource_CONFIRM
• www.oracle.comhttps://www.oracle.com/security-alerts/cpujan2022.htmlx_refsource_MISC
• www.oracle.comhttps://www.oracle.com/security-alerts/cpuapr2022.htmlx_refsource_MISC
• www.oracle.comhttps://www.oracle.com/security-alerts/cpujul2022.htmlx_refsource_MISC