CVE-2021-45105 | Apache Log4j2 does not always protect from infinite recursion in lookup evaluation

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.

Published: 2021-12-18 Last update: 2026-05-29 Assigner: [email protected] Source: [email protected]

Conclusion & alert: CVE-2021-45105 is rated Moderate Risk (57.7/100): CVSS Medium severity, with high exploitation likelihood (EPSS 74.02%, 99th percentile). Core evidence: EPSS ranks this CVE among the most likely to be exploited in the near term. Mandatory action: High exploitation likelihood—assess exposure and prioritize remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2021-45105

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-01 74.54% 74.02% -0.52%
2 2026-05-11 70.43% 74.54% +4.11%
3 2026-04-09 70.43%

Full EPSS history (94 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-45105

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
5.9 3.1 MEDIUM
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
2.2 3.6 [email protected]
5.9 3.1 MEDIUM
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
2.2 3.6 134c704f-9b21-4f2e-91b3-4a467353bcc0
4.3 2.0 MEDIUM
AV:N/AC:M/Au:N/C:N/I:N/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:M)
Exploitation needs some favorable conditions, but not exceptional ones.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:N)
No confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:P)
Partial availability impact.
8.6 2.9 [email protected]

Weakness enumeration for CVE-2021-45105

GitHub Security Advisory for CVE-2021-45105

GHSA-p6xc-xr62-6r2g · Severity: high · Ecosystem: maven — Apache Log4j2 vulnerable to Improper Input Validation and Uncontrolled Recursion

OS Trackers for CVE-2021-45105

vendor priority summary link
debian not yet assigned CVE-2021-45105 not yet assigned priority: Debian including 1 source packages (apache-log4j2), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2021-45105
redhat medium https://access.redhat.com/security/cve/CVE-2021-45105
suse high CVE-2021-45105 severity important: SUSE including 25 source package names (5.0.0-beta1.2.122:log4j-2.17.0-4.13.1, 5.0.0-beta1.2.122:log4j-jcl-2.17.0-4.13.1, …), 134 product×package rows across 66 product lines (Container suse/manager/5.0/x86_64/server, Container suse/manager/5.0/x86_64/server-attestation, … (66 product lines)): Fixed 73, Known Not Affected 61. https://www.suse.com/security/cve/CVE-2021-45105/
ubuntu medium CVE-2021-45105 medium priority: Ubuntu including 1 source packages (apache-log4j2), 14 status rows across 14 suites (bionic, focal, hirsute, impish, jammy, kinetic, lunar, mantic, noble, oracular, plucky, questing, upstream, xenial): not-affected 8, released 5, needed 1. https://ubuntu.com/security/CVE-2021-45105

Affected software / configurations for CVE-2021-45105

Vendor Product Version Raw CPE
apache log4j >= 2.0, < 2.3.1 cpe:2.3:a:apache:log4j:*:*:*:*:*:*:*:*
apache log4j >= 2.4, < 2.12.3 cpe:2.3:a:apache:log4j:*:*:*:*:*:*:*:*
apache log4j >= 2.13.0, <= 2.16.0 cpe:2.3:a:apache:log4j:*:*:*:*:*:*:*:*
netapp cloud_manager cpe:2.3:a:netapp:cloud_manager:-:*:*:*:*:*:*:*
debian debian_linux 10.0 cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*
debian debian_linux 11.0 cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:*
sonicwall email_security <= 10.0.12 cpe:2.3:a:sonicwall:email_security:*:*:*:*:*:*:*:*
sonicwall network_security_manager >= 2.0, < 3.0 cpe:2.3:a:sonicwall:network_security_manager:*:*:*:*:on-premises:*:*:*
sonicwall network_security_manager >= 2.0, < 3.0 cpe:2.3:a:sonicwall:network_security_manager:*:*:*:*:saas:*:*:*
sonicwall web_application_firewall >= 3.0.0, < 3.1.0 cpe:2.3:a:sonicwall:web_application_firewall:*:*:*:*:*:*:*:*
sonicwall 6bk1602-0aa12-0tp0_firmware < 2.7.0 cpe:2.3:o:sonicwall:6bk1602-0aa12-0tp0_firmware:*:*:*:*:*:*:*:*
sonicwall 6bk1602-0aa22-0tp0_firmware < 2.7.0 cpe:2.3:o:sonicwall:6bk1602-0aa22-0tp0_firmware:*:*:*:*:*:*:*:*
sonicwall 6bk1602-0aa32-0tp0_firmware < 2.7.0 cpe:2.3:o:sonicwall:6bk1602-0aa32-0tp0_firmware:*:*:*:*:*:*:*:*
sonicwall 6bk1602-0aa42-0tp0_firmware < 2.7.0 cpe:2.3:o:sonicwall:6bk1602-0aa42-0tp0_firmware:*:*:*:*:*:*:*:*
sonicwall 6bk1602-0aa52-0tp0_firmware < 2.7.0 cpe:2.3:o:sonicwall:6bk1602-0aa52-0tp0_firmware:*:*:*:*:*:*:*:*
oracle agile_engineering_data_management 6.2.1.0 cpe:2.3:a:oracle:agile_engineering_data_management:6.2.1.0:*:*:*:*:*:*:*
oracle agile_plm 9.3.6 cpe:2.3:a:oracle:agile_plm:9.3.6:*:*:*:*:*:*:*
oracle agile_plm_mcad_connector 3.6 cpe:2.3:a:oracle:agile_plm_mcad_connector:3.6:*:*:*:*:*:*:*
oracle autovue_for_agile_product_lifecycle_management 21.0.2 cpe:2.3:a:oracle:autovue_for_agile_product_lifecycle_management:21.0.2:*:*:*:*:*:*:*
oracle banking_deposits_and_lines_of_credit_servicing 2.12.0 cpe:2.3:a:oracle:banking_deposits_and_lines_of_credit_servicing:2.12.0:*:*:*:*:*:*:*
oracle banking_enterprise_default_management 2.7.1 cpe:2.3:a:oracle:banking_enterprise_default_management:2.7.1:*:*:*:*:*:*:*
oracle banking_enterprise_default_management 2.12.0 cpe:2.3:a:oracle:banking_enterprise_default_management:2.12.0:*:*:*:*:*:*:*
oracle banking_loans_servicing 2.12.0 cpe:2.3:a:oracle:banking_loans_servicing:2.12.0:*:*:*:*:*:*:*
oracle banking_party_management 2.7.0 cpe:2.3:a:oracle:banking_party_management:2.7.0:*:*:*:*:*:*:*
oracle banking_payments 14.5 cpe:2.3:a:oracle:banking_payments:14.5:*:*:*:*:*:*:*
oracle banking_platform 2.6.2 cpe:2.3:a:oracle:banking_platform:2.6.2:*:*:*:*:*:*:*
oracle banking_platform 2.7.1 cpe:2.3:a:oracle:banking_platform:2.7.1:*:*:*:*:*:*:*
oracle banking_platform 2.12.0 cpe:2.3:a:oracle:banking_platform:2.12.0:*:*:*:*:*:*:*
oracle banking_trade_finance 14.5 cpe:2.3:a:oracle:banking_trade_finance:14.5:*:*:*:*:*:*:*
oracle banking_treasury_management 14.5 cpe:2.3:a:oracle:banking_treasury_management:14.5:*:*:*:*:*:*:*
oracle business_intelligence 5.5.0.0.0 cpe:2.3:a:oracle:business_intelligence:5.5.0.0.0:*:*:*:enterprise:*:*:*
oracle communications_asap 7.3 cpe:2.3:a:oracle:communications_asap:7.3:*:*:*:*:*:*:*
oracle communications_billing_and_revenue_management 12.0.0.4 cpe:2.3:a:oracle:communications_billing_and_revenue_management:12.0.0.4:*:*:*:*:*:*:*
oracle communications_billing_and_revenue_management 12.0.0.5 cpe:2.3:a:oracle:communications_billing_and_revenue_management:12.0.0.5:*:*:*:*:*:*:*
oracle communications_cloud_native_core_console 1.9.0 cpe:2.3:a:oracle:communications_cloud_native_core_console:1.9.0:*:*:*:*:*:*:*
oracle communications_cloud_native_core_network_function_cloud_native_environment 1.10.0 cpe:2.3:a:oracle:communications_cloud_native_core_network_function_cloud_native_environment:1.10.0:*:*:*:*:*:*:*
oracle communications_cloud_native_core_network_repository_function 1.15.0 cpe:2.3:a:oracle:communications_cloud_native_core_network_repository_function:1.15.0:*:*:*:*:*:*:*
oracle communications_cloud_native_core_network_repository_function 1.15.1 cpe:2.3:a:oracle:communications_cloud_native_core_network_repository_function:1.15.1:*:*:*:*:*:*:*
oracle communications_cloud_native_core_network_slice_selection_function 1.8.0 cpe:2.3:a:oracle:communications_cloud_native_core_network_slice_selection_function:1.8.0:*:*:*:*:*:*:*
oracle communications_cloud_native_core_policy 1.15.0 cpe:2.3:a:oracle:communications_cloud_native_core_policy:1.15.0:*:*:*:*:*:*:*
oracle communications_cloud_native_core_security_edge_protection_proxy 1.7.0 cpe:2.3:a:oracle:communications_cloud_native_core_security_edge_protection_proxy:1.7.0:*:*:*:*:*:*:*
oracle communications_cloud_native_core_service_communication_proxy 1.15.0 cpe:2.3:a:oracle:communications_cloud_native_core_service_communication_proxy:1.15.0:*:*:*:*:*:*:*
oracle communications_cloud_native_core_unified_data_repository 1.15.0 cpe:2.3:a:oracle:communications_cloud_native_core_unified_data_repository:1.15.0:*:*:*:*:*:*:*
oracle communications_convergence 3.0.2.2.0 cpe:2.3:a:oracle:communications_convergence:3.0.2.2.0:*:*:*:*:*:*:*
oracle communications_convergence 3.0.3.0 cpe:2.3:a:oracle:communications_convergence:3.0.3.0:*:*:*:*:*:*:*
oracle communications_convergent_charging_controller >= 12.0.1.0.0, <= 12.0.4.0.0 cpe:2.3:a:oracle:communications_convergent_charging_controller:*:*:*:*:*:*:*:*
oracle communications_convergent_charging_controller 6.0.1.0.0 cpe:2.3:a:oracle:communications_convergent_charging_controller:6.0.1.0.0:*:*:*:*:*:*:*
oracle communications_diameter_signaling_router >= 8.3.0.0, <= 8.5.1.0 cpe:2.3:a:oracle:communications_diameter_signaling_router:*:*:*:*:*:*:*:*
oracle communications_eagle_element_management_system 46.6 cpe:2.3:a:oracle:communications_eagle_element_management_system:46.6:*:*:*:*:*:*:*
oracle communications_eagle_ftp_table_base_retrieval 4.5 cpe:2.3:a:oracle:communications_eagle_ftp_table_base_retrieval:4.5:*:*:*:*:*:*:*
oracle communications_element_manager < 9.0 cpe:2.3:a:oracle:communications_element_manager:*:*:*:*:*:*:*:*
oracle communications_evolved_communications_application_server 7.1 cpe:2.3:a:oracle:communications_evolved_communications_application_server:7.1:*:*:*:*:*:*:*
oracle communications_interactive_session_recorder 6.3 cpe:2.3:a:oracle:communications_interactive_session_recorder:6.3:*:*:*:*:*:*:*
oracle communications_interactive_session_recorder 6.4 cpe:2.3:a:oracle:communications_interactive_session_recorder:6.4:*:*:*:*:*:*:*
oracle communications_ip_service_activator 7.4.0 cpe:2.3:a:oracle:communications_ip_service_activator:7.4.0:*:*:*:*:*:*:*
oracle communications_messaging_server 8.1 cpe:2.3:a:oracle:communications_messaging_server:8.1:*:*:*:*:*:*:*
oracle communications_network_charging_and_control >= 12.0.1.0.0, <= 12.0.4.0.0 cpe:2.3:a:oracle:communications_network_charging_and_control:*:*:*:*:*:*:*:*
oracle communications_network_charging_and_control 6.0.1.0.0 cpe:2.3:a:oracle:communications_network_charging_and_control:6.0.1.0.0:*:*:*:*:*:*:*
oracle communications_network_integrity 7.3.6 cpe:2.3:a:oracle:communications_network_integrity:7.3.6:*:*:*:*:*:*:*
oracle communications_performance_intelligence_center 10.4.0.3 cpe:2.3:a:oracle:communications_performance_intelligence_center:10.4.0.3:*:*:*:*:*:*:*
oracle communications_pricing_design_center 12.0.0.4 cpe:2.3:a:oracle:communications_pricing_design_center:12.0.0.4:*:*:*:*:*:*:*
oracle communications_pricing_design_center 12.0.0.5 cpe:2.3:a:oracle:communications_pricing_design_center:12.0.0.5:*:*:*:*:*:*:*
oracle communications_service_broker 6.2 cpe:2.3:a:oracle:communications_service_broker:6.2:*:*:*:*:*:*:*
oracle communications_services_gatekeeper 7.0 cpe:2.3:a:oracle:communications_services_gatekeeper:7.0:*:*:*:*:*:*:*
oracle communications_session_report_manager < 9.0 cpe:2.3:a:oracle:communications_session_report_manager:*:*:*:*:*:*:*:*
oracle communications_session_route_manager < 9.0 cpe:2.3:a:oracle:communications_session_route_manager:*:*:*:*:*:*:*:*
oracle communications_unified_inventory_management 7.3.5 cpe:2.3:a:oracle:communications_unified_inventory_management:7.3.5:*:*:*:*:*:*:*
oracle communications_unified_inventory_management 7.4.1 cpe:2.3:a:oracle:communications_unified_inventory_management:7.4.1:*:*:*:*:*:*:*
oracle communications_unified_inventory_management 7.4.2 cpe:2.3:a:oracle:communications_unified_inventory_management:7.4.2:*:*:*:*:*:*:*
oracle communications_user_data_repository 12.4 cpe:2.3:a:oracle:communications_user_data_repository:12.4:*:*:*:*:*:*:*
oracle communications_webrtc_session_controller 7.2.0.0 cpe:2.3:a:oracle:communications_webrtc_session_controller:7.2.0.0:*:*:*:*:*:*:*
oracle communications_webrtc_session_controller 7.2.1 cpe:2.3:a:oracle:communications_webrtc_session_controller:7.2.1:*:*:*:*:*:*:*
oracle data_integrator 12.2.1.3.0 cpe:2.3:a:oracle:data_integrator:12.2.1.3.0:*:*:*:*:*:*:*
oracle data_integrator 12.2.1.4.0 cpe:2.3:a:oracle:data_integrator:12.2.1.4.0:*:*:*:*:*:*:*
oracle e-business_suite 12.2 cpe:2.3:a:oracle:e-business_suite:12.2:*:*:*:*:*:*:*
oracle enterprise_manager_base_platform 13.4.0.0 cpe:2.3:a:oracle:enterprise_manager_base_platform:13.4.0.0:*:*:*:*:*:*:*
oracle enterprise_manager_base_platform 13.5.0.0 cpe:2.3:a:oracle:enterprise_manager_base_platform:13.5.0.0:*:*:*:*:*:*:*
oracle enterprise_manager_for_peoplesoft 13.4.1.1 cpe:2.3:a:oracle:enterprise_manager_for_peoplesoft:13.4.1.1:*:*:*:*:*:*:*
oracle enterprise_manager_for_peoplesoft 13.5.1.1 cpe:2.3:a:oracle:enterprise_manager_for_peoplesoft:13.5.1.1:*:*:*:*:*:*:*
oracle enterprise_manager_ops_center 12.4.0.0 cpe:2.3:a:oracle:enterprise_manager_ops_center:12.4.0.0:*:*:*:*:*:*:*

References for CVE-2021-45105

URL Tags
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
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