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UK Cyber Defence
VulnerabilityAnalyzed

CVE-2021-45046

Apache Log4j2 Deserialization of Untrusted Data Vulnerability

KEVCRITICAL 9.0EPSS 100.0%

Does this matter?

Known to be exploited in the wild (CISA KEV, CISA remediation deadline 22 May 2023). Treat as an emergency change: patch or isolate now, then hunt for prior compromise.

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.

CVSS 3.1
9.0 CRITICALCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H
EPSS
99.98% probability · 100th percentile
CISA KEV
Listed 1 May 2023 · due 22 May 2023 · used in ransomware campaigns
Weakness
CWE-917
Affected
apache/log4j · 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 · intel/system studio · siemens/sppa-t3000 ses3000 firmware · siemens/captial · siemens/comos · siemens/desigo cc advanced reports · siemens/desigo cc info center · siemens/e-car operation center · siemens/energy engage · siemens/energyip · siemens/energyip prepay · siemens/gma-manager · +35 more
Source
security@apache.org

CISA notes

Apply updates per vendor instructions. https://logging.apache.org/log4j/2.x/security.html; https://nvd.nist.gov/vuln/detail/CVE-2021-45046

References

Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.