GHSA-P6XC-XR62-6R2G
Vulnerability from github – Published: 2021-12-18 18:00 – Updated: 2026-06-09 10:26
VLAI
Summary
Apache Log4j2 vulnerable to Improper Input Validation and Uncontrolled Recursion
Details
Apache Log4j2 versions 2.0-alpha1 through 2.16.0 (excluding 2.12.3) 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 and 2.12.3.
Affected packages
Only the org.apache.logging.log4j:log4j-core package is directly affected by this vulnerability. The org.apache.logging.log4j:log4j-api should be kept at the same version as the org.apache.logging.log4j:log4j-core package to ensure compatability if in use.
Severity
8.6 (High)
{
"affected": [
{
"package": {
"ecosystem": "Maven",
"name": "org.apache.logging.log4j:log4j-core"
},
"ranges": [
{
"events": [
{
"introduced": "2.4.0"
},
{
"fixed": "2.12.3"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "Maven",
"name": "org.apache.logging.log4j:log4j-core"
},
"ranges": [
{
"events": [
{
"introduced": "2.13.0"
},
{
"fixed": "2.17.0"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "Maven",
"name": "org.apache.logging.log4j:log4j-core"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "2.3.1"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "Maven",
"name": "org.ops4j.pax.logging:pax-logging-log4j2"
},
"ranges": [
{
"events": [
{
"introduced": "1.8.0"
},
{
"fixed": "1.9.2"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "Maven",
"name": "org.ops4j.pax.logging:pax-logging-log4j2"
},
"ranges": [
{
"events": [
{
"introduced": "1.10.0"
},
{
"fixed": "1.10.9"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "Maven",
"name": "org.ops4j.pax.logging:pax-logging-log4j2"
},
"ranges": [
{
"events": [
{
"introduced": "1.11.0"
},
{
"fixed": "1.11.12"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "Maven",
"name": "org.ops4j.pax.logging:pax-logging-log4j2"
},
"ranges": [
{
"events": [
{
"introduced": "2.0.0"
},
{
"fixed": "2.0.13"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2021-45105"
],
"database_specific": {
"cwe_ids": [
"CWE-20",
"CWE-674"
],
"github_reviewed": true,
"github_reviewed_at": "2021-12-18T17:59:37Z",
"nvd_published_at": "2021-12-18T12:15:00Z",
"severity": "HIGH"
},
"details": "Apache Log4j2 versions 2.0-alpha1 through 2.16.0 (excluding 2.12.3) 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 and 2.12.3.\n\n\n# Affected packages\nOnly the `org.apache.logging.log4j:log4j-core` package is directly affected by this vulnerability. The `org.apache.logging.log4j:log4j-api` should be kept at the same version as the `org.apache.logging.log4j:log4j-core` package to ensure compatability if in use.",
"id": "GHSA-p6xc-xr62-6r2g",
"modified": "2026-06-09T10:26:50Z",
"published": "2021-12-18T18:00:07Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2021-45105"
},
{
"type": "WEB",
"url": "https://www.zerodayinitiative.com/advisories/ZDI-21-1541"
},
{
"type": "WEB",
"url": "https://www.oracle.com/security-alerts/cpujul2022.html"
},
{
"type": "WEB",
"url": "https://www.oracle.com/security-alerts/cpujan2022.html"
},
{
"type": "WEB",
"url": "https://www.oracle.com/security-alerts/cpuapr2022.html"
},
{
"type": "WEB",
"url": "https://www.kb.cert.org/vuls/id/930724"
},
{
"type": "WEB",
"url": "https://www.debian.org/security/2021/dsa-5024"
},
{
"type": "WEB",
"url": "https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-apache-log4j-qRuKNEbd"
},
{
"type": "WEB",
"url": "https://security.netapp.com/advisory/ntap-20211218-0001"
},
{
"type": "WEB",
"url": "https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-apache-log4j-qRuKNEbd"
},
{
"type": "WEB",
"url": "https://psirt.global.sonicwall.com/vuln-detail/SNWLID-2021-0032"
},
{
"type": "WEB",
"url": "https://logging.apache.org/log4j/2.x/security.html"
},
{
"type": "WEB",
"url": "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/SIG7FZULMNK2XF6FZRU4VWYDQXNMUGAJ"
},
{
"type": "WEB",
"url": "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/EOKPQGV24RRBBI4TBZUDQMM4MEH7MXCY"
},
{
"type": "WEB",
"url": "https://lists.debian.org/debian-lts-announce/2021/12/msg00017.html"
},
{
"type": "WEB",
"url": "https://cert-portal.siemens.com/productcert/pdf/ssa-501673.pdf"
},
{
"type": "WEB",
"url": "https://cert-portal.siemens.com/productcert/pdf/ssa-479842.pdf"
},
{
"type": "WEB",
"url": "http://www.openwall.com/lists/oss-security/2021/12/19/1"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H",
"type": "CVSS_V3"
}
],
"summary": "Apache Log4j2 vulnerable to Improper Input Validation and Uncontrolled Recursion"
}
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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.
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