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Log4jFramework / library · Apache

CVE-2023-26464

HIGH · 7.5 CVSS v3.1 Published 2023-03-10
Fix available
A fix is available. Upgrade to 2.0 or later.
See remediation →
84/100
Remediation priority · High
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
** UNSUPPORTED WHEN ASSIGNED ** When using the Chainsaw or SocketAppender components with Log4j 1.x on JRE less than 1.7, an attacker that manages to cause a logging entry involving a specially-crafted (ie, deeply nested) hashmap or hashtable (depending on which logging component is in use) to be processed could exhaust the available memory in the virtual machine and achieve Denial of Service when the object is deserialized. This issue affects Apache Log4j before 2. Affected users are recommended to update to Log4j 2.x. NOTE: This vulnerability only affects products that are no longer supported by the maintainer.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

In Log4j 1.x, the Chainsaw and SocketAppender components perform deserialization of logged objects. On JRE versions prior to 1.7, an attacker who can trigger logging of specially-crafted deeply nested hashmap or hashtable objects can cause excessive memory consumption during deserialization, leading to denial of service.

MitigationUpgrade to Log4j 2.x, which addresses this and other known vulnerabilities. If upgrading is not immediately feasible, remove or disable the affected Chainsaw and SocketAppender components and ensure logging inputs are strictly validated.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Log4jFramework / library
Affected:>= 1.0.4, < 2.0

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify installed Log4j 1.x version
    Search for log4j-*.jar files in your application and library directories, or check Maven/Gradle dependency manifests for log4j version. Examine the JAR filename or inspect the manifest file within the JAR for the version number.
    Affected if The version is 1.0.4 or higher but below 2.0 (e.g., 1.2.x, 1.3.x, 1.4.x)
  2. Check Java Runtime Environment version
    Run 'java -version' from the command line to determine the JRE version. Look for the major version number in the output.
    Affected if The JRE version is prior to 1.7 (Java 7)
  3. Determine if Chainsaw component is in use
    Search configuration files (log4j.xml, log4j.properties) for 'Chainsaw' appender references, or check for chainsaw*.jar files in the classpath. Inspect application code for Chainsaw usage.
    Affected if Chainsaw is configured or present in the runtime classpath
  4. Determine if SocketAppender is in use
    Search log4j configuration files for 'SocketAppender' entries, or review application code for SocketAppender instantiation. Check for network socket configurations related to logging.
    Affected if SocketAppender is configured or used in the logging setup

You are affected if Log4j 1.x version 1.0.4 to <2.0 is installed, the JRE is prior to version 1.7, and either Chainsaw or SocketAppender components are actively used in the logging configuration.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 2.0 or later
Fixed in 2.0
Interim mitigation

Upgrade to Log4j 2.x, which addresses this and other known vulnerabilities. If upgrading is not immediately feasible, remove or disable the affected Chainsaw and SocketAppender components and ensure logging inputs are strictly validated.

Recommended fix High confidence

Log4j 2.x (2.17.0 or later recommended)

  1. 1. Identify all dependencies in your project that reference Log4j 1.x (log4j:log4j < 2.0)
  2. 2. Remove all Log4j 1.x dependencies from your project's build configuration (Maven pom.xml, Gradle build.gradle, etc.)
  3. 3. Add Log4j 2.x dependencies to your project. For most applications, add: log4j-api and log4j-core (version 2.17.0 or later for security fixes)
  4. 4. If using Log4j 1.x programmatic configuration, rewrite configuration to use Log4j 2.x XML, JSON, or properties-based configuration
  5. 5. Update any code that directly references Log4j 1.x classes (org.apache.log4j) to use Log4j 2.x classes (org.apache.logging.log4j)
  6. 6. If using SLF4J as a logging facade, ensure the log4j-slf4j-impl binding is included for Log4j 2.x integration
  7. 7. Test the application thoroughly to verify logging functionality works correctly after migration
  8. 8. Remove any remaining references to Chainsaw or SocketAppender from Log4j 1.x if previously used
Caveat Log4j 1.x to 2.x has API and configuration changes; code using org.apache.log4j classes needs rewriting to use org.apache.logging.log4j, and configuration files require conversion to Log4j 2.x format

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Log4j Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing4.0 h
  • Review / QA2.0 h
12.0 hours of engineering $2,080
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2023-26464 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
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