Skip to content
Fencer Vulns
medium 5.9

CVE-2021-45105 json

Apache Log4j2 does not always protect from infinite recursion in lookup evaluation

published 2021-12-18 4 y ago modified 2026-08-25 2 mo ago also GHSA-p6xc-xr62-6r2g , EUVD-2021-2559

cvss
5.9
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
100.0%
EPSS 100.0% chance of exploitation in 30 days, percentile 99.9%
public exploits
0
none known

Summary

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.

Patch / fix

  • maven org.apache.logging.log4j:log4j-core 2.3.1, 2.12.3, 2.17.0
  • maven org.ops4j.pax.logging:pax-logging-log4j2 1.9.2, 1.10.9, 1.11.12, 2.0.13
  • Apache Software Foundation Apache Log4j2 2.3.1, 2.12.3, 2.17.0
  • apache-log4j2 Debian 14, Debian 13, Debian 12 2.17.0-1

debian advisories DEBIAN-CVE-2021-45105

  • apache-log4j2 Ubuntu 18.04 LTS 2.12.4-0ubuntu0.1
  • apache-log4j2 Ubuntu 20.04 LTS 2.17.0-0.20.04.1

ubuntu advisories UBUNTU-CVE-2021-45105

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • rh-sso7-keycloak red hat single sign on 7.5 15.0.6-1.redhat_00001.1.el8sso
  • rh-sso7-keycloak-server red hat single sign on 7.5 15.0.6-1.redhat_00001.1.el8sso
  • rh-sso7-keycloak red hat single sign on 7.5 15.0.6-1.redhat_00001.1.el7sso
  • rh-sso7-keycloak-server red hat single sign on 7.5 15.0.6-1.redhat_00001.1.el7sso
  • eap7-log4j jboss enterprise application platform 7.4 2.17.1-1.redhat_00001.1.el7eap
  • eap7-log4j jboss enterprise application platform 7.4 2.17.1-1.redhat_00001.1.el8eap

red hat advisories RHSA-2022:1463RHSA-2022:1462RHSA-2022:1296RHSA-2022:1297

  • log4j openSUSE Leap 15.2 2.17.0-lp152.3.12.1
  • log4j openSUSE Leap 15.3 2.17.0-4.13.1

opensuse advisories openSUSE-SU-2021:1605-1openSUSE-SU-2021:4118-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2021-45105 updated cvss 5.9

log4j-core: DoS in log4j 2.x with Thread Context Map (MDC) input data contains a recursive lookup and context lookup pattern

  • Red Hat Decision Manager 7 log4j-api Red Hat Integration Camel Quarkus 1 log4j-core Red Hat OpenShift Container Platform 3.11 openshift3/ose-logging-elasticsearch5 Red Hat streams for Apache Kafka log4j-core
    affected: workaround, no fix available
  • Red Hat OpenShift Logging 5.0 openshift-logging/elasticsearch6-rhel8 v5.0.11-2
    fixed: vendor fix RHSA-2022:0047
  • Red Hat OpenShift Logging 5.1 openshift-logging/elasticsearch6-rhel8 v6.8.1-82
    fixed: vendor fix RHSA-2022:0042
  • Red Hat OpenShift Logging 5.2 openshift-logging/elasticsearch6-rhel8 v6.8.1-83
    fixed: vendor fix RHSA-2022:0043
  • Red Hat OpenShift Logging 5.3 openshift-logging/elasticsearch6-rhel8 v6.8.1-84
    fixed: vendor fix RHSA-2022:0044
  • Red Hat AMQ Streams 1.6.6
    fixed: vendor fix RHSA-2022:0219
  • Red Hat Data Grid 8.2.3
    fixed: vendor fix RHSA-2022:0205
  • Red Hat Fuse 7.8.2, 7.9.1, 7.10.1
    fixed: vendor fix RHSA-2022:0203
show 11 more
  • Red Hat Integration Camel Extensions for Quarkus 2.2
    fixed: vendor fix RHSA-2022:0222
  • Red Hat Integration Camel-K 1.6.3
    fixed: vendor fix RHSA-2022:0223
  • Red Hat JBoss EAP 7.4 for RHEL 7 Server eap7-log4j 2.17.1-1.redhat_00001.1.el7eap
    fixed: vendor fix RHSA-2022:1296
  • Red Hat JBoss EAP 7.4 for RHEL 8 eap7-log4j 2.17.1-1.redhat_00001.1.el8eap
    fixed: vendor fix RHSA-2022:1297
  • Red Hat JBoss Enterprise Application Platform log4j-api 2.17.1.redhat-00001
    fixed: vendor fix RHSA-2022:0216
  • Red Hat OpenShift Container Platform 4.6 openshift4/ose-logging-elasticsearch6 v4.6.0-202112201736.p0.gce7f68c.assembly.stream
    fixed: vendor fix RHSA-2022:0026
  • Red Hat Single Sign-On 7
    fixed: vendor fix RHSA-2022:1469
  • Red Hat Single Sign-On 7.5 for RHEL 7 Server rh-sso7-keycloak 15.0.6-1.redhat_00001.1.el7sso, rh-sso7-keycloak-server 15.0.6-1.redhat_00001.1.el7sso
    fixed: vendor fix RHSA-2022:1462
  • Red Hat Single Sign-On 7.5 for RHEL 8 rh-sso7-keycloak 15.0.6-1.redhat_00001.1.el8sso, rh-sso7-keycloak-server 15.0.6-1.redhat_00001.1.el8sso
    fixed: vendor fix RHSA-2022:1463
  • Red Hat Vert.x 4.1.8
    fixed: vendor fix RHSA-2022:0083
  • Red Hat A-MQ Clients 2 log4j-core Red Hat OpenShift Logging 5.0 openshift-logging/fluentd-rhel8 v5.0.11-2, openshift-logging/kibana6-rhel8 v5.0.11-2, openshift-logging/eventrouter-rhel8 v5.0.11-2, openshift-logging/logging-curator5-rhel8 v5.0.11-2, openshift-logging/elasticsearch-proxy-rhel8 v5.0.11-2, openshift-logging/elasticsearch-rhel8-operator v5.0.11-2, +3 more Red Hat OpenShift Logging 5.1 openshift-logging/fluentd-rhel8 v1.7.4-88, openshift-logging/kibana6-rhel8 v6.8.1-93, openshift-logging/eventrouter-rhel8 v0.3.0-81, openshift-logging/elasticsearch-proxy-rhel8 v1.0.0-87, openshift-logging/elasticsearch-rhel8-operator v5.1.6-3, openshift-logging/cluster-logging-rhel8-operator v5.1.6-3, +2 more Red Hat OpenShift Logging 5.2 openshift-logging/fluentd-rhel8 v1.7.4-87, openshift-logging/kibana6-rhel8 v6.8.1-94, openshift-logging/eventrouter-rhel8 v0.3.0-82, openshift-logging/logging-curator5-rhel8 v5.8.1-60, openshift-logging/elasticsearch-proxy-rhel8 v1.0.0-88, openshift-logging/elasticsearch-rhel8-operator v5.2.5-4, +4 more Red Hat OpenShift Logging 5.3 openshift-logging/fluentd-rhel8 v1.7.4-89, openshift-logging/kibana6-rhel8 v6.8.1-95, openshift-logging/eventrouter-rhel8 v0.3.0-83, openshift-logging/logging-curator5-rhel8 v5.8.1-61, openshift-logging/elasticsearch-proxy-rhel8 v1.0.0-89, openshift-logging/elasticsearch-rhel8-operator v5.3.2-3, +4 more Red Hat AMQ Broker 7 log4j-core
    +13 more products
    Red Hat build of Quarkus log4j-core Red Hat Enterprise Linux 6 log4j, log4j-manual, log4j-javadoc Red Hat Enterprise Linux 7 log4j, log4j-manual, log4j-javadoc Red Hat Enterprise Linux 8 log4j12, log4j12-javadoc Red Hat JBoss EAP 7.4 for RHEL 7 Server eap7-xom 1.3.7-1.redhat_00001.1.el7eap, eap7-ecj 3.26.0-1.redhat_00002.1.el7eap, eap7-yasson 1.0.10-1.redhat_00001.1.el7eap, eap7-wildfly 7.4.4-3.GA_redhat_00011.1.el7eap, eap7-objectweb-asm 9.1.0-1.redhat_00002.1.el7eap, eap7-narayana 5.11.4-1.Final_redhat_00001.1.el7eap, +58 more Red Hat JBoss EAP 7.4 for RHEL 8 eap7-xom 1.3.7-1.redhat_00001.1.el8eap, eap7-ecj 3.26.0-1.redhat_00002.1.el8eap, eap7-yasson 1.0.10-1.redhat_00001.1.el8eap, eap7-wildfly 7.4.4-3.GA_redhat_00011.1.el8eap, eap7-objectweb-asm 9.1.0-1.redhat_00002.1.el8eap, eap7-narayana 5.11.4-1.Final_redhat_00001.1.el8eap, +56 more Red Hat JBoss Enterprise Application Platform pom.xml, c3 0.6.0, c3 0.7.1, d3 5.9.2, ms 2.0.0, ms 2.1.2, +1456 more Red Hat JBoss Enterprise Application Platform 6 log4j Red Hat JBoss Enterprise Application Platform Expansion Pack log4j-core Red Hat OpenShift Container Platform 4 openshift4/ose-metering-hive, openshift4/ose-metering-hadoop, openshift4/ose-metering-presto Red Hat OpenShift Container Platform 4.6 openshift4/ose-logging-fluentd v4.6.0-202112201736.p0.gce7f68c.assembly.stream, openshift4/ose-logging-kibana6 v4.6.0-202112201736.p0.gce7f68c.assembly.stream, openshift4/ose-metering-hadoop v4.6.0-202112150825.p0.gf381145.assembly.stream, openshift4/ose-metering-presto v4.6.0-202112150825.p0.g190688a.assembly.stream, openshift4/ose-egress-dns-proxy v4.6.0-202112141645.p0.g618b71d.assembly.stream, openshift4/ose-logging-curator5 v4.6.0-202201061151.p0.gce7f68c.assembly.4.6.53, +3 more Red Hat Process Automation 7 log4j-core Red Hat Satellite 6 log4j-over-slf4j
    not affected: vulnerable code not present

1 more not affected in the full advisory

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
5 mo ago

Exploit prediction

100.00% chance of exploitation in the next 30 days, higher than 99.9% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CISA ADP 3.1 5.9 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD 3.1 5.9 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
CNA 3.1 5.9 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD 2.0 4.3 AV:N/AC:M/Au:N/C:N/I:N/A:P
GitHub 3.1 8.6 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H

Affected packages

ecosystem package affected fixed in
maven org.apache.logging.log4j:log4j-core
>=2.4.0, <2.12.3
>=2.13.0, <2.17.0
<2.3.1
2.12.3
2.17.0
2.3.1
maven org.ops4j.pax.logging:pax-logging-log4j2
>=1.8.0, <1.9.2
>=1.10.0, <1.10.9
>=1.11.0, <1.11.12
>=2.0.0, <2.0.13
1.9.2
1.10.9
1.11.12
2.0.13

Affected products

  • Apache Software Foundation Apache Log4j2

Classification

Weakness
  • CWE-20 Improper Input Validation
  • CWE-674 Uncontrolled Recursion
Technology feeds

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.