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ExploitedIn CISA KEVFix available

CVE-2021-45046

Log4Shell

Exploitation confirmed. First attested on 2023-05-01 by CISA-ADP, CISA KEV, GCVE · kevintel.

  • Published2021-12-14
  • Fixed in2.16.0 · 2.12.2 · 2.3.1
  • TwinCVE-2021-44228
  • WeaknessCWE-917

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

It was found that the fix to address CVE-2021-44228 in Apache Log4j 2.15.0 was incomplete in certain non-default configurations. This could allows attackers with control over Thread Context Map (MDC) input data when the logging configuration uses a non-default Pattern Layout with either a Context Lookup (for example, $${ctx:loginId}) or a Thread Context Map pattern (%X, %mdc, or %MDC) to craft malicious input data using a JNDI Lookup pattern resulting in an information leak and remote code execution in some environments and local code execution in all environments. Log4j 2.16.0 (Java 8) and 2.12.2 (Java 7) fix this issue by removing support for message lookup patterns and disabling JNDI functionality by default.

Timeline

dates in UTC
  1. 2021-12-1419:15CVE publishedNVD
  2. 2023-05-01Added to the CISA KEV catalogCISA KEV
  3. 2023-05-01Listed as exploited by GCVEGCVE
  4. 2023-05-01Exploitation first reportedCISA KEV
  5. 2025-02-0419:31SSVC exploitation set to activeCISA-ADP

Observed activity

isMalicious corpus · updated 2026-11-03 21:37 UTC
Indicators tagged with this CVE, per day0 indicators over 7 days
Block these indicators
  • Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2021-45046?format=txt
  • CSV export: https://api.ismalicious.com/edl/cve/CVE-2021-45046?format=csv
  • TAXII collection of exploited CVEs
  • The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD · OSV
Apache Log4j
BranchAffectedFixed in
2.x≥ 2.13.0, < 2.16.02.16.0
2.x≥ 2.0.1, < 2.12.22.12.2
2.x≥ 2.4.0, < 2.12.22.12.2
2.3< 2.3.12.3.1
2.0= 2.0no fix published
Siemens desigo cc advanced reports
BranchAffectedFixed in
4.0= 4.0no fix published
4.1= 4.1no fix published
4.2= 4.2no fix published
5.0= 5.0no fix published
5.1= 5.1no fix published
Siemens energyip
BranchAffectedFixed in
8.5= 8.5no fix published
8.6= 8.6no fix published
8.7= 8.7no fix published
9.0= 9.0no fix published

53 more products in the sources.

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Products declared by the CNA1 product

As apache, the CNA that assigned this CVE, declared them in the CVE record; versions as written.

  • Apache Software Foundation Apache Log4j
    Affected
    • ≥ Apache Log4j2, < 2.16.0fixed in 2.16.0custom

Source: the CNA record (CVE Program), © The MITRE Corporation,CVE Terms of UseCVE recordupdated 2023-10-26

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Packages

  • apache-log4j2Ubuntu:20.04:LTSall versions · fixed in 2.16.0-0.20.04.1
  • apache-log4j2Debian:14all versions · fixed in 2.16.0-1
  • apache-log4j2Debian:13all versions · fixed in 2.16.0-1
  • apache-log4j2Debian:12all versions · fixed in 2.16.0-1
  • apache-log4j2Debian:11all versions · fixed in 2.16.0-1~deb11u1
  • apache-log4j2Debian:10all versions · fixed in 2.16.0-1~deb10u1
  • disruptoropenSUSE:Leap 15.3all versions · fixed in 3.4.4-3.3.1
  • disruptoropenSUSE:Leap 15.2all versions · fixed in 3.4.4-lp152.2.3.1

33 more package ranges on OSV.dev

Vendor advisories

  • CVE-2021-45046 Red Hat Product Security123 products fixed · 4 known affected

    log4j-core: DoS in log4j 2.x with thread context message pattern and context lookup pattern (incomplete fix for CVE-2021-44228)

    log4j-core as a component of Red Hat Integration Camel Quarkus 1 · opendaylight as a component of Red Hat OpenStack Platform 13 (Queens) · opendaylight.src as a component of Red Hat OpenStack Platform 13 (Queens) · +1 more

  • RHSA-2025:1747 Red Hat Product Security52 products fixed

    Red Hat Security Advisory: Red Hat JBoss Enterprise Application Platform 7.3.12 security update

  • RHSA-2025:1746 Red Hat Product Security37 products fixed

    Red Hat Security Advisory: Red Hat JBoss Enterprise Application Platform 7.1.9 on RHEL 7 security update

  • RHSA-2022:1299 Red Hat Product Security1 product fixed

    Red Hat Security Advisory: Red Hat JBoss Enterprise Application Platform 7.4.4 security update

  • RHSA-2022:1297 Red Hat Product Security2 products fixed

    Red Hat Security Advisory: Red Hat JBoss Enterprise Application Platform 7.4.4 security update

  • RHSA-2022:1296 Red Hat Product Security2 products fixed

    Red Hat Security Advisory: Red Hat JBoss Enterprise Application Platform 7.4.4 security update

22 more advisories

Full record on NVD

Fix

  1. Update Apache Log4j to 2.16.0 · 2.12.2 · 2.3.1
  2. CISA’s required action: Apply updates per vendor instructions.due 2023-05-22
  3. Vendor fix Red Hat Product Security RHSA-2025:1747 · 52 productsBefore applying this update, ensure all previously released errata relevant to your system have been applied. Also, back up your existing installation, including all applications, configuration files, databases and database settings. For details on how to apply this update, refer to: https://access…
  4. Vendor fix Red Hat Product Security RHSA-2025:1746 · 37 productsBefore applying this update, ensure all previously released errata relevant to your system have been applied. Also, back up your existing installation, including all applications, configuration files, databases and database settings. For details on how to apply this update, refer to: https://access…
  5. Vendor fix Red Hat Product Security RHSA-2022:1299 · 1 productBefore applying this update, back up your existing Red Hat JBoss Enterprise Application Platform installation and deployed applications. The References section of this erratum contains a download link (you must log in to download the update).
  6. Vendor fix Red Hat Product Security RHSA-2022:1297 · 2 productsBefore applying this update, back up your existing Red Hat JBoss Enterprise Application Platform installation and deployed applications. For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258
  7. Vendor fix Red Hat Product Security RHSA-2022:0223 · 1 productBefore applying this update, make sure all previously released errata relevant to your system have been applied. For details on how to apply this update, refer to: https://access.redhat.com/articles/11258
  8. Vendor fix Red Hat Product Security RHSA-2022:0222 · 1 productBefore applying this update, make sure all previously released errata relevant to your system have been applied. For details on how to apply this update, refer to: https://access.redhat.com/articles/11258

Advisories and patches

Detection

read 2026-11-03 22:42 UTC
Nuclei template
available
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof-of-concept repositories
11 repositories, unverifiedcckuailong/Log4j_CVE-2021-45046BobTheShoplifter/CVE-2021-45046-Infotejas-nagchandi/CVE-2021-45046pravin-pp/log4j2-CVE-2021-45046mergebase/log4j-samples
PoC-in-GitHub
Metasploit modules
1 moduleauxiliary/scanner/http/log4shell_scannerrank: normalModule metadata: Metasploit Framework, © Rapid7, Inc., BSD-3-Clause.
Metasploit Framework

CISA Known Exploited Vulnerability

Date Added
2023-05-01
Patch Due Date
2023-05-22
Ransomware Use
Known
Required Action
Apply updates per vendor instructions.

Sources

Identifiers

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H
Published
2021-12-14
Last Modified
2026-06-17
NVD status
Analyzed
GitHub Advisory
GHSA-7rjr-3q55-vv33

Frequently asked questions

What is CVE-2021-45046?

It was found that the fix to address CVE-2021-44228 in Apache Log4j 2.15.0 was incomplete in certain non-default configurations. This could allows attackers with control over Thread Context Map (MDC) input data when the logging configuration uses a non-default Pattern Layout with either a Context Lookup (for example, $${ctx:loginId}) or a Thread Context Map pattern (%X, %mdc, or %MDC) to craft malicious input data using a JNDI Lookup pattern resulting in an information leak and remote code execution in some environments and local code execution in all environments. Log4j 2.16.0 (Java 8) and 2.12.2 (Java 7) fix this issue by removing support for message lookup patterns and disabling JNDI functionality by default.

Is CVE-2021-45046 actively exploited?

Yes. CVE-2021-45046 is on the CISA Known Exploited Vulnerabilities (KEV) catalog, meaning it has been confirmed as actively exploited in the wild. CISA requires federal agencies to patch by 2023-05-22.

What is the CVSS score for CVE-2021-45046?

CVE-2021-45046 has a CVSS v3 base score of 9 (CRITICAL severity), with vector string CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H.

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