CVE-2021-45105

CRITICALNVD 5.99.0
EchelonGraph scoreHIGH confidence

“▲” 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.

Triggered by: EPSS exploit prediction (continuous uplift above 30%)
Sources: EPSS, GitHub Security Advisory, NVD CVSS v3
Trending — 4 sources updated this weekElevated

Also known asEUVD-2021-2559 (ENISA EUVD) · GHSA-p6xc-xr62-6r2g (GitHub Security Advisories)Source: ENISA EUVD

9.0EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines (the SSVC decision on this page).
  • High exploitation likelihood — EPSS >99.9%
  • Public exploit or proof-of-concept code is available
CISA-KEV: Not listedEPSS PROB: >99.9%CVSS: 5.9Exploit: Public PoCExposed services: Not assessed

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."

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
9.0CRITICALhigh confidence
EG Risk
79
EG 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
Patch available. Sources: cert.
CERT

VU#930724 - Apache Log4j allows insecure JNDI lookups

https://www.kb.cert.org/vuls/id/930724
Web page

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

https://www.debian.org/security/2021/dsa-5024
Web page

Vulnerabilities in Apache Log4j Library Affecting Cisco Products: December 2021

https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-apache-log4j-qRuKNEbd
Web pageMentions a patch (unverified)

Security :: Apache Logging Services

https://logging.apache.org/log4j/2.x/security.html
Web page

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

Patch Availability(23)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
ubuntuliblog4j2-java-doc (2.12.4-0ubuntu0.1) @ bionic2026-11-01ubuntu
ubuntuliblog4j2-java (2.17.0-0.21.04.1) @ hirsute2026-11-01ubuntu
redhatlog4j-api2022-04-20redhat
redhatrh-sso7-keycloak-0:15.0.6-1.redhat_00001.1.el7sso2022-04-20redhat
redhatrh-sso7-keycloak-0:15.0.6-1.redhat_00001.1.el8sso2022-04-20redhat
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:v6.8.1-832022-01-10redhat
redhatopenshift-logging/elasticsearch6-rhel8:v6.8.1-842022-01-10redhat
redhatopenshift-logging/elasticsearch6-rhel8:v6.8.1-822022-01-10redhat
mavenorg.apache.logging.log4j:log4j-core @ 2.12.3 (fixes >= 2.4.0, < 2.12.3)—ghsa
mavenorg.apache.logging.log4j:log4j-core @ 2.17.0 (fixes >= 2.13.0, < 2.17.0)—ghsa
mavenorg.apache.logging.log4j:log4j-core @ 2.3.1 (fixes < 2.3.1)—ghsa
mavenorg.ops4j.pax.logging:pax-logging-log4j2 @ 1.10.9 (fixes >= 1.10.0, < 1.10.9)—ghsa
mavenorg.ops4j.pax.logging:pax-logging-log4j2 @ 1.11.12 (fixes >= 1.11.0, < 1.11.12)—ghsa
mavenorg.ops4j.pax.logging:pax-logging-log4j2 @ 2.0.13 (fixes >= 2.0.0, < 2.0.13)—ghsa
mavenorg.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)
PackageVulnerable rangeFix by version rangeDependents
org.apache.logging.log4j:log4j-core2.0 ... 2.3 (19 versions)
  • 2.4.0 up to 2.12.3: fixed in 2.12.3
  • 2.13.0 up to 2.17.0: fixed in 2.17.0
  • every version up to 2.3.1: fixed in 2.3.1
—
org.ops4j.pax.logging:pax-logging-log4j22.0.0 ... 2.0.9 (13 versions)
  • 1.8.0 up to 1.9.2: fixed in 1.9.2
  • 1.10.0 up to 1.10.9: fixed in 1.10.9
  • 1.11.0 up to 1.11.12: fixed in 1.11.12
  • 2.0.0 up to 2.0.13: fixed in 2.0.13
—
Debian:10(1)
PackageVulnerable rangeFix by version rangeDependents
apache-log4j22.11.1-2 ... 2.16.0-1~deb11u1 (9 versions)
  • every version up to 2.17.0-1~deb10u1: fixed in 2.17.0-1~deb10u1
—
Debian:11(1)
PackageVulnerable rangeFix by version rangeDependents
apache-log4j22.13.3-1 ... 2.17.0-1~deb10u1 (8 versions)
  • every version up to 2.17.0-1~deb11u1: fixed in 2.17.0-1~deb11u1
—
Debian:12(1)
PackageVulnerable rangeFix by version rangeDependents
apache-log4j2—
  • every version up to 2.17.0-1: fixed in 2.17.0-1
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
apache-log4j2—
  • every version up to 2.17.0-1: fixed in 2.17.0-1
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
apache-log4j2—
  • every version up to 2.17.0-1: fixed in 2.17.0-1
—
Debian:9(1)
PackageVulnerable rangeFix by version rangeDependents
apache-log4j22.10.0-1 ... 2.8.2-2 (9 versions)
  • every version up to 2.12.3-0+deb9u1: fixed in 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 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.

  1. 2026-11-01 13:30 UTCVendor advisory
  2. 2026-11-01 13:30 UTCGHSA enrichmentGHSA-p6xc-xr62-6r2g · GitHub severity HIGH · GitHub CVSS 8.6
  3. 2026-11-01 08:30 UTCGHSA enrichmentGHSA-p6xc-xr62-6r2g · GitHub severity HIGH · GitHub CVSS 8.6
  4. 2026-11-01 08:30 UTCEG score recompute
  5. 2026-10-31 11:55 UTCEG score recompute
  6. 2026-10-31 11:55 UTCVendor advisory
  7. 2026-10-30 10:20 UTCEG score recompute
  8. 2026-10-30 10:20 UTCVendor advisory
  9. 2026-10-29 08:46 UTCEG score recompute
  10. 2026-10-29 08:46 UTCVendor advisory
  11. 2026-10-28 07:08 UTCEG score recompute
  12. 2026-10-28 07:08 UTCVendor advisory
  13. 2026-10-27 16:28 UTCEPSS rescoreEPSS >99.9% · 99th percentile
  14. 2026-10-27 05:32 UTCEG score recompute
  15. 2026-10-27 05:32 UTCVendor advisory
  16. 2026-10-25 23:54 UTCVendor advisory
  17. 2026-10-25 18:19 UTCEG score recompute
  18. 2026-10-24 22:18 UTCEG score recompute
  19. 2026-10-24 22:18 UTCVendor advisory
  20. 2026-10-23 20:44 UTCEG score recompute
  21. 2026-10-23 20:44 UTCVendor advisory
  22. 2026-10-22 19:09 UTCEG score recompute
  23. 2026-10-22 19:09 UTCVendor advisory
  24. 2026-10-21 17:29 UTCEG score recompute
  25. 2026-10-21 17:29 UTCVendor advisory
Show 50 more
  1. 2026-10-20 15:54 UTCEG score recompute
  2. 2026-10-20 15:54 UTCVendor advisory
  3. 2026-10-19 14:18 UTCEG score recompute
  4. 2026-10-19 14:18 UTCVendor advisory
  5. 2026-10-18 12:43 UTCVendor advisory
  6. 2026-10-18 08:51 UTCEG score recompute
  7. 2026-10-17 11:06 UTCEG score recompute
  8. 2026-10-17 11:06 UTCVendor advisory
  9. 2026-10-16 09:31 UTCEG score recompute
  10. 2026-10-16 09:31 UTCVendor advisory
  11. 2026-10-15 07:55 UTCEG score recompute
  12. 2026-10-15 07:55 UTCVendor advisory
  13. 2026-10-14 03:53 UTCEG score recompute
  14. 2026-10-14 03:53 UTCVendor advisory
  15. 2026-10-12 23:47 UTCVendor advisory
  16. 2026-10-12 19:07 UTCEG score recompute
  17. 2026-10-11 23:32 UTCEG score recompute
  18. 2026-10-02 17:40 UTCOSV refresh
  19. 2026-09-30 15:44 UTCEG score recompute
  20. 2026-09-13 14:54 UTCOSV refresh
  21. 2026-08-25 16:34 UTCEG score recompute
  22. 2026-08-25 16:34 UTCVendor advisory
  23. 2026-08-24 07:57 UTCOSV refresh
  24. 2026-08-16 02:11 UTCEPSS rescoreEPSS >99.9% · 99th percentile
  25. 2026-08-08 04:19 UTCOSV refresh
  26. 2026-07-23 02:05 UTCEG score recompute
  27. 2026-07-22 21:21 UTCEG score recompute▲ 3.10
  28. 2026-07-22 21:21 UTCVendor advisory
  29. 2026-07-18 05:29 UTCOSV refresh
  30. 2026-06-30 02:00 UTCOSV refresh
  31. 2026-06-15 17:46 UTCEPSS rescoreEPSS >99.9% · 99th percentile
  32. 2026-06-13 22:58 UTCEPSS rescoreEPSS 74% · 98th percentile
  33. 2026-06-12 23:10 UTCEPSS rescoreEPSS 74% · 98th percentile
  34. 2026-06-12 14:40 UTCOSV refresh
  35. 2026-06-11 13:58 UTCEPSS rescoreEPSS 74% · 98th percentile
  36. 2026-06-10 22:16 UTCEPSS rescoreEPSS 74% · 98th percentile
  37. 2026-06-10 13:20 UTCEPSS rescoreEPSS 74% · 98th percentile
  38. 2026-06-08 14:15 UTCEPSS rescoreEPSS 74% · 98th percentile
  39. 2026-06-07 15:23 UTCEPSS rescoreEPSS 74% · 98th percentile
  40. 2026-06-05 22:45 UTCEPSS rescoreEPSS 74% · 98th percentile
  41. 2026-06-05 06:09 UTCEPSS rescoreEPSS 74% · 98th percentile
  42. 2026-06-04 13:10 UTCEPSS rescoreEPSS 74% · 98th percentile
  43. 2026-06-02 20:11 UTCEPSS rescoreEPSS 74% · 98th percentile
  44. 2026-06-01 13:50 UTCEPSS rescoreEPSS 74% · 98th percentile
  45. 2026-05-31 00:15 UTCEPSS rescoreEPSS 75% · 98th percentile
  46. 2026-05-29 13:42 UTCEPSS rescoreEPSS 75% · 98th percentile
  47. 2026-05-28 13:43 UTCEPSS rescoreEPSS 75% · 98th percentile
  48. 2026-05-27 13:39 UTCEPSS rescoreEPSS 75% · 98th percentile
  49. 2026-05-26 06:06 UTCEG score recompute
  50. 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_exploit
    Published Dec 20, 2021

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

    Open source ↗
  • GitHub PoCcckuailong/Log4j_dos_CVE-2021-45105
    Published 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

Frequently asked(5)

What is CVE-2021-45105?
CVE-2021-45105 is a critical-severity vulnerability; its CVE record was 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 the CVE record for CVE-2021-45105 published?
The CVE record for CVE-2021-45105 was published on December 18, 2021. That is the record's publication date; the vulnerability itself may have been made public earlier. EchelonGraph's copy of the record carries a last-modified date of August 25, 2026; the record at its source may have been updated since.
Is CVE-2021-45105 actively exploited?
CVE-2021-45105 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a >99.9% probability of exploitation in the next 30 days (99th percentile of EPSS-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 + FIRST EPSS + GHSA into a combined EG score of 9.0 (CRITICAL).
How do I remediate CVE-2021-45105?
A fix for CVE-2021-45105 is available: update to the fixed version the vendor names in its advisory. 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." The vendor advisories EchelonGraph has for CVE-2021-45105 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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