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.
CVE-2021-45105
“▲” beside the score: it is higher than NVD's CVSS score.
Score elevated to 9.0 because EPSS predicted >99.9% probability of exploitation within the next 30 days (99th percentile of EPSS-scored CVEs) when EchelonGraph scored this CVE. NVD baseline CVSS 5.9 retained for reference. Confidence: see factors.
Also known asEUVD-2021-2559 (ENISA EUVD) · GHSA-p6xc-xr62-6r2g (GitHub Security Advisories)Source: ENISA EUVD
- High exploitation likelihood — EPSS >99.9%
- Public exploit or proof-of-concept code is available
A fix is available — apply it.
Fixed versions, as the CVE record's CNA (Apache Software Foundation) states them in the record's workaround: "Implement one of the following mitigation techniques: * Java 8 (or later) users should upgrade to release 2.17.0."
- CVSS v3
- 5.9
- EG Score
- 9.0CRITICALhigh confidence
- EG Risk
- 79EG Risk 79/100
EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.
How it’s computed (value × EchelonGraph’s weight)Severity86% × 45%Impact severity (EG Severity): CVSS 8.6 of 10. Never the KEV-floored or EPSS-lifted EG Score.Exploitation>99.9% × 40%FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.Automatability0% × 15%CISA's SSVC Automatable value: no (Vulnrichment).SSVC (CISA's decision table, applied by EchelonGraph): Track at every mission impact level.Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.Action: A fix is available. Apply it within your standard update timelines. - EPSS PROB
- >99.9%
- EPSS %ILE
- 99th
- KEV
- Not listed
What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)
The EG score (9.0): severity, escalated by confirmed exploitation. This CVE's 9.0 is EPSS's lift toward 9.0 from its impact severity (EG Severity, CVSS 8.6 HIGH): a likelihood of exploitation, not impact.
- EG Severity
- 8.6 HIGHCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
- EG Likelihood
- >99.9% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-31). FIRST's exploitation probability, not an EchelonGraph model.
- Confirmed exploitation
- None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
- EG Priority
- SSVC Track at medium mission impactTrack at every mission impact level.CISA BOD 26-04: 60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.
SSVC (CISA's decision table, applied by EchelonGraph)Track at every mission impact level.
A fix is available. Apply it within your standard update timelines.
Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table
BOD 26-04 (CISA's remediation timeline, Table 1)60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.
The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it
Published
December 18, 2021
Last Modified
August 25, 2026
Advisory Details (9)
Auto-updated Aug 25, 2026[SECURITY] [DSA 5024-1] apache-log4j2 security update
https://www.debian.org/security/2021/dsa-5024Vulnerabilities in Apache Log4j Library Affecting Cisco Products: December 2021
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-apache-log4j-qRuKNEbdSecurity :: Apache Logging Services
https://logging.apache.org/log4j/2.x/security.htmloss-security - CVE-2021-45105: Apache Log4j2 does not always protect from infinite recursion in lookup evaluation
http://www.openwall.com/lists/oss-security/2021/12/19/1Vendor Advisories for CVE-2021-45105(19)
These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.
- RHSA-2022:1463Red Hat Product SecurityLow
Red Hat Security Advisory: Red Hat Single Sign-On 7.5.2 security update on RHEL 8
- RHSA-2022:1462Red Hat Product SecurityLow
Red Hat Security Advisory: Red Hat Single Sign-On 7.5.2 security update on RHEL 7
- RHSA-2022:1469Red Hat Product SecurityLow
Red Hat Security Advisory: Red Hat Single Sign-On 7.5.2 security update
- RHSA-2022:1299Red Hat Product SecurityLow
Red Hat Security Advisory: Red Hat JBoss Enterprise Application Platform 7.4.4 security update
- RHSA-2022:1297Red Hat Product SecurityLow
Red Hat Security Advisory: Red Hat JBoss Enterprise Application Platform 7.4.4 security update
- RHSA-2022:1296Red Hat Product SecurityLow
Red Hat Security Advisory: Red Hat JBoss Enterprise Application Platform 7.4.4 security update
- RHSA-2022:0223Red Hat Product SecurityMedium
Red Hat Security Advisory: Red Hat Integration Camel-K 1.6.3 release and security update
- RHSA-2022:0222Red Hat Product SecurityMedium
Red Hat Security Advisory: Red Hat Integration Camel Extensions for Quarkus 2.2 security update
- +11 more
Patch Availability(23)
| Vendor / Ecosystem | Fix (by version range) / Patch | Released | Source |
|---|---|---|---|
| ubuntu | liblog4j2-java-doc (2.12.4-0ubuntu0.1) @ bionic | 2026-11-01 | ubuntu |
| ubuntu | liblog4j2-java (2.17.0-0.21.04.1) @ hirsute | 2026-11-01 | ubuntu |
| redhat | log4j-api | 2022-04-20 | redhat |
| redhat | rh-sso7-keycloak-0:15.0.6-1.redhat_00001.1.el7sso | 2022-04-20 | redhat |
| redhat | rh-sso7-keycloak-0:15.0.6-1.redhat_00001.1.el8sso | 2022-04-20 | redhat |
| redhat | eap7-log4j-0:2.17.1-1.redhat_00001.1.el8eap | 2022-04-11 | redhat |
| redhat | eap7-log4j-0:2.17.1-1.redhat_00001.1.el7eap | 2022-04-11 | redhat |
| redhat | org.apache.logging.log4j/log4j-api:2.17.1.redhat-00001 | 2022-04-11 | redhat |
| redhat | log4j-core | 2022-01-20 | redhat |
| redhat | patch | 2022-01-20 | redhat |
| redhat | patch | 2022-01-20 | redhat |
| redhat | openshift4/ose-logging-elasticsearch6:v4.6.0-202112201736.p0.gce7f68c.assembly.stream | 2022-01-12 | redhat |
| redhat | openshift-logging/elasticsearch6-rhel8:v5.0.11-2 | 2022-01-10 | redhat |
| redhat | openshift-logging/elasticsearch6-rhel8:v6.8.1-83 | 2022-01-10 | redhat |
| redhat | openshift-logging/elasticsearch6-rhel8:v6.8.1-84 | 2022-01-10 | redhat |
| redhat | openshift-logging/elasticsearch6-rhel8:v6.8.1-82 | 2022-01-10 | redhat |
| maven | org.apache.logging.log4j:log4j-core @ 2.12.3 (fixes >= 2.4.0, < 2.12.3) | — | ghsa |
| maven | org.apache.logging.log4j:log4j-core @ 2.17.0 (fixes >= 2.13.0, < 2.17.0) | — | ghsa |
| maven | org.apache.logging.log4j:log4j-core @ 2.3.1 (fixes < 2.3.1) | — | ghsa |
| maven | org.ops4j.pax.logging:pax-logging-log4j2 @ 1.10.9 (fixes >= 1.10.0, < 1.10.9) | — | ghsa |
| maven | org.ops4j.pax.logging:pax-logging-log4j2 @ 1.11.12 (fixes >= 1.11.0, < 1.11.12) | — | ghsa |
| maven | org.ops4j.pax.logging:pax-logging-log4j2 @ 2.0.13 (fixes >= 2.0.0, < 2.0.13) | — | ghsa |
| maven | org.ops4j.pax.logging:pax-logging-log4j2 @ 1.9.2 (fixes >= 1.8.0, < 1.9.2) | — | ghsa |
Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.
Affected Packages
(8 across 7 ecosystems)
Maven(2)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| org.apache.logging.log4j:log4j-core | 2.0 ... 2.3 (19 versions) |
| — |
| org.ops4j.pax.logging:pax-logging-log4j2 | 2.0.0 ... 2.0.9 (13 versions) |
| — |
Debian:10(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| apache-log4j2 | 2.11.1-2 ... 2.16.0-1~deb11u1 (9 versions) |
| — |
Debian:11(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| apache-log4j2 | 2.13.3-1 ... 2.17.0-1~deb10u1 (8 versions) |
| — |
Debian:12(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| apache-log4j2 | — |
| — |
Debian:13(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| apache-log4j2 | — |
| — |
Debian:14(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| apache-log4j2 | — |
| — |
Debian:9(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| apache-log4j2 | 2.10.0-1 ... 2.8.2-2 (9 versions) |
| — |
Weakness Classification(2)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Additional Vendor Advisories
(2)
Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.
Data Freshness Timeline
(refreshed 15× in last 7d / 42× in last 30d)
Each row is a time one of our pipelines fetched, updated or re-scored this CVE. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.
A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. 12 repeat rows among the latest 87 are merged into the row they repeat.
- 2026-11-01 13:30 UTCVendor advisory
- 2026-11-01 13:30 UTCGHSA enrichmentGHSA-p6xc-xr62-6r2g · GitHub severity HIGH · GitHub CVSS 8.6
- 2026-11-01 08:30 UTCGHSA enrichmentGHSA-p6xc-xr62-6r2g · GitHub severity HIGH · GitHub CVSS 8.6
- 2026-11-01 08:30 UTCEG score recompute
- 2026-10-31 11:55 UTCEG score recompute
- 2026-10-31 11:55 UTCVendor advisory
- 2026-10-30 10:20 UTCEG score recompute
- 2026-10-30 10:20 UTCVendor advisory
- 2026-10-29 08:46 UTCEG score recompute
- 2026-10-29 08:46 UTCVendor advisory
- 2026-10-28 07:08 UTCEG score recompute
- 2026-10-28 07:08 UTCVendor advisory
- 2026-10-27 16:28 UTCEPSS rescoreEPSS >99.9% · 99th percentile
- 2026-10-27 05:32 UTCEG score recompute
- 2026-10-27 05:32 UTCVendor advisory
- 2026-10-25 23:54 UTCVendor advisory
- 2026-10-25 18:19 UTCEG score recompute
- 2026-10-24 22:18 UTCEG score recompute
- 2026-10-24 22:18 UTCVendor advisory
- 2026-10-23 20:44 UTCEG score recompute
- 2026-10-23 20:44 UTCVendor advisory
- 2026-10-22 19:09 UTCEG score recompute
- 2026-10-22 19:09 UTCVendor advisory
- 2026-10-21 17:29 UTCEG score recompute
- 2026-10-21 17:29 UTCVendor advisory
Show 50 moreShow fewer
- 2026-10-20 15:54 UTCEG score recompute
- 2026-10-20 15:54 UTCVendor advisory
- 2026-10-19 14:18 UTCEG score recompute
- 2026-10-19 14:18 UTCVendor advisory
- 2026-10-18 12:43 UTCVendor advisory
- 2026-10-18 08:51 UTCEG score recompute
- 2026-10-17 11:06 UTCEG score recompute
- 2026-10-17 11:06 UTCVendor advisory
- 2026-10-16 09:31 UTCEG score recompute
- 2026-10-16 09:31 UTCVendor advisory
- 2026-10-15 07:55 UTCEG score recompute
- 2026-10-15 07:55 UTCVendor advisory
- 2026-10-14 03:53 UTCEG score recompute
- 2026-10-14 03:53 UTCVendor advisory
- 2026-10-12 23:47 UTCVendor advisory
- 2026-10-12 19:07 UTCEG score recompute
- 2026-10-11 23:32 UTCEG score recompute
- 2026-10-02 17:40 UTCOSV refresh
- 2026-09-30 15:44 UTCEG score recompute
- 2026-09-13 14:54 UTCOSV refresh
- 2026-08-25 16:34 UTCEG score recompute
- 2026-08-25 16:34 UTCVendor advisory
- 2026-08-24 07:57 UTCOSV refresh
- 2026-08-16 02:11 UTCEPSS rescoreEPSS >99.9% · 99th percentile
- 2026-08-08 04:19 UTCOSV refresh
- 2026-07-23 02:05 UTCEG score recompute
- 2026-07-22 21:21 UTCEG score recompute▲ 3.10
- 2026-07-22 21:21 UTCVendor advisory
- 2026-07-18 05:29 UTCOSV refresh
- 2026-06-30 02:00 UTCOSV refresh
- 2026-06-15 17:46 UTCEPSS rescoreEPSS >99.9% · 99th percentile
- 2026-06-13 22:58 UTCEPSS rescoreEPSS 74% · 98th percentile
- 2026-06-12 23:10 UTCEPSS rescoreEPSS 74% · 98th percentile
- 2026-06-12 14:40 UTCOSV refresh
- 2026-06-11 13:58 UTCEPSS rescoreEPSS 74% · 98th percentile
- 2026-06-10 22:16 UTCEPSS rescoreEPSS 74% · 98th percentile
- 2026-06-10 13:20 UTCEPSS rescoreEPSS 74% · 98th percentile
- 2026-06-08 14:15 UTCEPSS rescoreEPSS 74% · 98th percentile
- 2026-06-07 15:23 UTCEPSS rescoreEPSS 74% · 98th percentile
- 2026-06-05 22:45 UTCEPSS rescoreEPSS 74% · 98th percentile
- 2026-06-05 06:09 UTCEPSS rescoreEPSS 74% · 98th percentile
- 2026-06-04 13:10 UTCEPSS rescoreEPSS 74% · 98th percentile
- 2026-06-02 20:11 UTCEPSS rescoreEPSS 74% · 98th percentile
- 2026-06-01 13:50 UTCEPSS rescoreEPSS 74% · 98th percentile
- 2026-05-31 00:15 UTCEPSS rescoreEPSS 75% · 98th percentile
- 2026-05-29 13:42 UTCEPSS rescoreEPSS 75% · 98th percentile
- 2026-05-28 13:43 UTCEPSS rescoreEPSS 75% · 98th percentile
- 2026-05-27 13:39 UTCEPSS rescoreEPSS 75% · 98th percentile
- 2026-05-26 06:06 UTCEG score recompute
- 2026-05-26 06:06 UTCVendor advisory
Publicly available exploits
(2 references)Public exploit code is referenced for this CVE (2 GitHub PoCs). Defenders should treat patch urgency accordingly.
- GitHub PoCiAmSOScArEd/log4j2_dos_exploitPublished Dec 20, 2021
log4j2 dos exploit,CVE-2021-45105 exploit,Denial of Service poc
Open source ↗ - GitHub PoCcckuailong/Log4j_dos_CVE-2021-45105Published Dec 18, 2021
Log4j_dos_CVE-2021-45105
Open source ↗
Past incidents using this CVE
(1)This CVE was central to one or more publicly-documented breaches. Each card links to authoritative reporting at the time of the incident.
- Log4Shell (Apache Log4j)Dec 2021
JNDI lookup injection in Log4j, a ubiquitous Java logging library. Pre-auth unauthenticated RCE; Apache Foundation called it the worst vulnerability in a decade. Active exploitation continues 3+ years later.
Source: Wired
Related CVEs(same product + same vendor + same CWE)
Same product
10 shownDebian:10:apache-log4j2 · Debian:9:apache-log4j2 · Debian:11:apache-log4j2
- CVE-2021-44228EG 10.0 KEVEPSS p100CRITICAL
- CVE-2021-45046EG 9.0 KEVEPSS p100CRITICAL
- CVE-2021-44832NVD 6.6EG 9.0EPSS p100CRITICAL
- CVE-2020-9488EG 3.7EPSS p95LOW
- CVE-2017-5645EG 9.8EPSS p100CRITICAL
- CVE-2026-34480EG 7.5HIGH
- CVE-2025-68161EG 4.8MEDIUM
- CVE-2026-34481EG 7.5HIGH
- CVE-2026-34479EG 7.5HIGH
- CVE-2026-49844EG 5.9MEDIUM
Same vendor
8 shownredhat:RHSA-2022:0083 · redhat:RHSA-2022:1296 · redhat:RHSA-2022:0203
- CVE-2021-44832NVD 6.6EG 9.0EPSS p100CRITICAL
- CVE-2021-45046EG 9.0 KEVEPSS p100CRITICAL
- CVE-2022-23307NVD 8.8EG 9.8EPSS p99CRITICAL
- CVE-2022-23305EG 9.8EPSS p99CRITICAL
- CVE-2022-23302EG 8.9EPSS p99HIGH
- CVE-2021-4104NVD 7.5EG 8.9EPSS p100HIGH
- CVE-2021-44228EG 10.0 KEVEPSS p100CRITICAL
- CVE-2021-38153EG 5.9EPSS p94MEDIUM
Same CWE
10 shownCWE-20
- CVE-2021-43242EG 7.6HIGH
- CVE-2021-44422EG 7.8HIGH
- CVE-2021-45419EG 8.8HIGH
- CVE-2021-45462EG 7.5EPSS p92HIGH
- CVE-2021-44548EG 9.8EPSS p93CRITICAL
- CVE-2021-44228EG 10.0 KEVEPSS p100CRITICAL
- CVE-2021-43803NVD 7.5EG 8.0EPSS p99HIGH
- CVE-2021-45687EG 9.8CRITICAL
- CVE-2021-45711EG 7.5HIGH
- CVE-2021-43802EG 9.9CRITICAL
Frequently asked(5)
What is CVE-2021-45105?
When was the CVE record for CVE-2021-45105 published?
Is CVE-2021-45105 actively exploited?
What is the CVSS score of CVE-2021-45105?
How do I remediate CVE-2021-45105?
Dependency Blast Radius
See which npm, PyPI, Go, and Maven packages are affected by CVE-2021-45105
Is Your Infrastructure Affected by CVE-2021-45105?
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