What is CVE-2021-45046?

CVE-2021-45046 is a critical-severity vulnerability in Apache Log4j, classified under Improper Neutralization of Special Elements used in an Expression Language Statement (Expression Language Injection). CVSS score: 9.0/10. Published 2021-12-14.

How severe is CVE-2021-45046?

Critical severity. CVSS v3 base score is 9.0 out of 10.

Is CVE-2021-45046 known to be exploited?

Yes. CVE-2021-45046 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2023-05-01), indicating it is being actively exploited. 348 public proof-of-concept repositories are indexed.

Log4Shell — Apache Log4j RCE

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.

Vulnerability class: Log4Shell (CVE-2021-44228)

EPSS: 1.000 (100.0th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 9.0 (Critical). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H.

Affected products

Apache Log4j — versions 2.0
Apache Software Foundation Log4j — versions Apache Log4j2
Cvat Computer_vision_annotation_tool
Intel Audio_development_kit
Intel Datacenter_manager
Intel Genomics_kernel_library
Intel Oneapi
Intel Secure_device_onboard
Intel Sensor_solution_firmware_development_kit
Intel System_debugger

Weakness classification (CWE)

CWE-917 — Improper Neutralization of Special Elements used in an Expression Language Statement (Expression Language Injection)

CISA KEV (Known Exploited Vulnerabilities)

This CVE is on the CISA KEV catalog, added on 2023-05-01. CISA KEV inclusion means CISA has confirmed in-the-wild exploitation; US federal agencies are required to remediate within a published due date.

BOD 22-01 due date: 2023-05-22.

Required action: Apply updates per vendor instructions.

Known ransomware campaign use: yes.

Public proof-of-concept exploits

References

security@apache.org (x_refsource_CONFIRM, Third Party Advisory)
security@apache.org (x_refsource_CONFIRM, Third Party Advisory)
security@apache.org (x_refsource_MISC, Not Applicable)
security@apache.org (mailing-list, x_refsource_MLIST, Mailing List, Third Party Advisory, Mitigation)
security@apache.org (x_refsource_CONFIRM, Release Notes, Mitigation, Vendor Advisory)
security@apache.org (US Government Resource, x_refsource_CERT-VN, Third Party Advisory, third-party-advisory)
security@apache.org (x_refsource_CONFIRM, Third Party Advisory)
security@apache.org (x_refsource_CONFIRM, Third Party Advisory)
security@apache.org (x_refsource_CISCO, vendor-advisory, Third Party Advisory)
security@apache.org (mailing-list, x_refsource_MLIST, Mailing List, Third Party Advisory)

Frequently asked questions

What is CVE-2021-45046?: CVE-2021-45046 is a critical-severity vulnerability in Apache Log4j, classified under Improper Neutralization of Special Elements used in an Expression Language Statement (Expression Language Injection). CVSS score: 9.0/10. Published 2021-12-14.
How severe is CVE-2021-45046?: Critical severity. CVSS v3 base score is 9.0 out of 10.
Is CVE-2021-45046 known to be exploited?: Yes. CVE-2021-45046 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2023-05-01), indicating it is being actively exploited. 348 public proof-of-concept repositories are indexed.