CVE-2021-45105

CRITICALNVD 5.99.0▲
EchelonGraph scoreMEDIUM confidence

Score elevated to 9.0 because EPSS predicts 100% probability of exploitation within the next 30 days (top 0.0% of all CVEs). NVD baseline CVSS 5.9 retained for reference. Confidence: see factors.

Triggered by: EPSS exploit prediction ≥85%
Sources: epss, nvd
Trending — 3 sources updated this weekElevated
9.0EG
EchelonGraph verdictPatch this weekExploitation is likely or a public exploit exists.
  • High exploitation likelihood — EPSS 100%
CISA-KEV: Not listedEPSS PROB: 100%CVSS: 5.9Exploit: Elevated riskExposed: 0

A fix is available — apply it.

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.

CVSS v3
5.9
EG Score
9.0(medium)
EG Risk
80(Track)
EG Risk 80/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity90% × 45%
Exploitation100% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
100%
EPSS %ILE
100%
KEV
Not listed

Published

December 18, 2021

Last Modified

August 25, 2026

Advisory Details (9)

Auto-updated Aug 25, 2026
🔬 Proof of concept available. Patch available. Sources: cert.
cert

VU#930724 - Apache Log4j allows insecure JNDI lookups

https://www.kb.cert.org/vuls/id/930724
generic

[SECURITY] [DSA 5024-1] apache-log4j2 security update

https://www.debian.org/security/2021/dsa-5024
generic🟡 PoC Available

Vulnerabilities in Apache Log4j Library Affecting Cisco Products: December 2021

https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-apache-log4j-qRuKNEbd
generic

NetApp Product Security

https://security.netapp.com/advisory/ntap-20211218-0001/
generic

Security Advisory

https://psirt.global.sonicwall.com/vuln-detail/SNWLID-2021-0032
generic Patch Available

Security :: Apache Logging Services

https://logging.apache.org/log4j/2.x/security.html
generic
https://cert-portal.siemens.com/productcert/pdf/ssa-501673.pdf
generic
https://cert-portal.siemens.com/productcert/pdf/ssa-479842.pdf
generic

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

http://www.openwall.com/lists/oss-security/2021/12/19/1

Vendor 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.

Patch Availability(16)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntuliblog4j2-java (2.17.0-0.21.10.1) @ impish2026-08-25ubuntu
ubuntuliblog4j2-java (2.17.1-0.21.10.1) @ impish2026-08-25ubuntu
redhatrh-sso7-keycloak-0:15.0.6-1.redhat_00001.1.el8sso2022-04-20redhat
redhatlog4j-api2022-04-20redhat
redhatrh-sso7-keycloak-0:15.0.6-1.redhat_00001.1.el7sso2022-04-20redhat
redhateap7-log4j-0:2.17.1-1.redhat_00001.1.el8eap2022-04-11redhat
redhateap7-log4j-0:2.17.1-1.redhat_00001.1.el7eap2022-04-11redhat
redhatorg.apache.logging.log4j/log4j-api:2.17.1.redhat-000012022-04-11redhat
redhatlog4j-core2022-01-20redhat
redhatpatch2022-01-20redhat
redhatpatch2022-01-20redhat
redhatopenshift4/ose-logging-elasticsearch6:v4.6.0-202112201736.p0.gce7f68c.assembly.stream2022-01-12redhat
redhatopenshift-logging/elasticsearch6-rhel8:v5.0.11-22022-01-10redhat
redhatopenshift-logging/elasticsearch6-rhel8:v6.8.1-822022-01-10redhat
redhatopenshift-logging/elasticsearch6-rhel8:v6.8.1-842022-01-10redhat
redhatopenshift-logging/elasticsearch6-rhel8:v6.8.1-832022-01-10redhat

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)
PackageVulnerable rangeFixed inDependents
org.apache.logging.log4j:log4j-core2.0 ... 2.3 (19 versions)2.3.1—
org.ops4j.pax.logging:pax-logging-log4j22.0.0 ... 2.0.9 (13 versions)2.0.13—
Debian:10(1)
PackageVulnerable rangeFixed inDependents
apache-log4j22.11.1-2 ... 2.16.0-1~deb11u1 (9 versions)2.17.0-1~deb10u1—
Debian:11(1)
PackageVulnerable rangeFixed inDependents
apache-log4j22.13.3-1 ... 2.17.0-1~deb10u1 (8 versions)2.17.0-1~deb11u1—
Debian:12(1)
PackageVulnerable rangeFixed inDependents
apache-log4j2—2.17.0-1—
Debian:13(1)
PackageVulnerable rangeFixed inDependents
apache-log4j2—2.17.0-1—
Debian:14(1)
PackageVulnerable rangeFixed inDependents
apache-log4j2—2.17.0-1—
Debian:9(1)
PackageVulnerable rangeFixed inDependents
apache-log4j22.10.0-1 ... 2.8.2-2 (9 versions)2.12.3-0+deb9u1—

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 3× in last 7d / 5× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. 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. Most recent first.

  1. 2026-08-25 16:34 UTCEG score recompute
  2. 2026-08-25 16:34 UTCVendor advisory
  3. 2026-08-24 07:57 UTCOSV refresh
  4. 2026-08-16 02:11 UTCEPSS rescore
  5. 2026-08-08 04:19 UTCOSV refresh
  6. 2026-07-23 02:05 UTCEG score recompute
  7. 2026-07-22 21:21 UTCEG score recompute▲ 3.10
  8. 2026-07-22 21:21 UTCVendor advisory
  9. 2026-07-18 05:29 UTCOSV refresh
  10. 2026-06-30 02:00 UTCOSV refresh
  11. 2026-06-15 17:46 UTCEPSS rescore
  12. 2026-06-13 22:58 UTCEPSS rescore
  13. 2026-06-13 22:58 UTCEPSS rescore
  14. 2026-06-12 23:10 UTCEPSS rescore
  15. 2026-06-12 14:40 UTCOSV refresh
  16. 2026-06-11 13:58 UTCEPSS rescore
  17. 2026-06-11 13:58 UTCEPSS rescore
  18. 2026-06-10 22:16 UTCEPSS rescore
  19. 2026-06-10 22:16 UTCEPSS rescore
  20. 2026-06-10 13:20 UTCEPSS rescore
  21. 2026-06-08 14:15 UTCEPSS rescore
  22. 2026-06-08 14:15 UTCEPSS rescore
  23. 2026-06-07 15:23 UTCEPSS rescore
  24. 2026-06-07 15:23 UTCEPSS rescore
  25. 2026-06-05 22:45 UTCEPSS rescore
Show 17 more
  1. 2026-06-05 06:09 UTCEPSS rescore
  2. 2026-06-05 06:09 UTCEPSS rescore
  3. 2026-06-04 13:10 UTCEPSS rescore
  4. 2026-06-04 13:10 UTCEPSS rescore
  5. 2026-06-02 20:11 UTCEPSS rescore
  6. 2026-06-02 20:11 UTCEPSS rescore
  7. 2026-06-01 13:50 UTCEPSS rescore
  8. 2026-06-01 13:50 UTCEPSS rescore
  9. 2026-05-31 00:15 UTCEPSS rescore
  10. 2026-05-31 00:15 UTCEPSS rescore
  11. 2026-05-29 13:42 UTCEPSS rescore
  12. 2026-05-28 13:43 UTCEPSS rescore
  13. 2026-05-28 13:43 UTCEPSS rescore
  14. 2026-05-27 13:39 UTCEPSS rescore
  15. 2026-05-27 13:39 UTCEPSS rescore
  16. 2026-05-26 06:06 UTCEG score recompute
  17. 2026-05-26 06:06 UTCVendor advisory

Publicly available exploits

(2 references)

Working exploit code is in the public domain (2 GitHub PoCs). Defenders should treat patch urgency accordingly — public PoCs typically lead to mass-exploitation within 24-72 hours.

  • GitHub PoCiAmSOScArEd/log4j2_dos_exploit
    First seen Dec 20, 2021

    log4j2 dos exploit,CVE-2021-45105 exploit,Denial of Service poc

    Open source ↗
  • GitHub PoCcckuailong/Log4j_dos_CVE-2021-45105
    First seen 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 vendor + same CWE)

Frequently asked(5)

What is CVE-2021-45105?
CVE-2021-45105 is a critical vulnerability published on December 18, 2021. 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…
When was CVE-2021-45105 disclosed?
CVE-2021-45105 was first published in the National Vulnerability Database on December 18, 2021, with the most recent update on August 25, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2021-45105 actively exploited?
CVE-2021-45105 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 100% probability of exploitation in the next 30 days, which ranks it in the top 0.0% of all scored CVEs.
What is the CVSS score of CVE-2021-45105?
CVE-2021-45105 has a CVSS v3 base score of 5.9 (NVD). EchelonGraph synthesises NVD + CISA KEV + FIRST EPSS + GHSA into a combined EG score of 9.0.
How do I remediate CVE-2021-45105?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-45105, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2021-45105

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