Vulnerability-Lookup

FKIE_CVE-2026-84501

Vulnerability from fkie_nvd - Published: 2026-09-16 10:16 - Updated: 2026-09-16 20:17

Severity

5.3 (Medium) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

Summary

An unauthenticated attacker can inject arbitrary fake log lines into Apache ZooKeeper's operational log by sending a crafted add_auth("ensemble", ...) request containing newline characters (\n). When the ensemble name doesn't match, EnsembleAuthenticationProvider.handleAuthentication() logs the raw, unsanitized name via LOG.warn(). Because SLF4J's {} placeholder preserves embedded newlines, the attacker can forge complete log entries — with arbitrary timestamps, log levels, class names, and messages — that are visually indistinguishable from genuine ZooKeeper log output. This issue affects Apache ZooKeeper: from 3.9.0 through 3.9.5, from 3.8.0 through 3.8.6. Users are recommended to upgrade to version 3.8.7 or 3.9.6, which fixes the issue.

References

	URL	Tags
	security@apache.org	https://lists.apache.org/thread/ohby1g6zjt72p0w79rhbr41nczzvr33y
	af854a3a-2127-422b-91ae-364da2661108	http://www.openwall.com/lists/oss-security/2026/09/15/7

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "collectionURL": "https://repo.maven.apache.org/maven2",
          "defaultStatus": "unaffected",
          "packageName": "org.apache.zookeeper:zookeeper",
          "packageURL": "pkg:maven/org.apache.zookeeper/zookeeper",
          "product": "Apache ZooKeeper",
          "vendor": "Apache Software Foundation",
          "versions": [
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              "status": "affected",
              "version": "3.9.0",
              "versionType": "maven"
            },
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              "lessThanOrEqual": "3.8.6",
              "status": "affected",
              "version": "3.8.0",
              "versionType": "maven"
            }
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      "source": "security@apache.org"
    }
  ],
  "cveTags": [],
  "descriptions": [
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    }
  ],
  "id": "CVE-2026-84501",
  "lastModified": "2026-09-16T20:17:34.620",
  "metrics": {
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          "attackVector": "NETWORK",
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          "baseScore": 5.3,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "NONE",
          "integrityImpact": "LOW",
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          "scope": "UNCHANGED",
          "userInteraction": "NONE",
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          "version": "3.1"
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        "impactScore": 1.4,
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "type": "Secondary"
      }
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    "ssvcV203": [
      {
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        "ssvcData": {
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          "options": [
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          "role": "CISA Coordinator",
          "timestamp": "2026-09-16T19:42:27.138755Z",
          "version": "2.0.3"
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  "published": "2026-09-16T10:16:53.557",
  "references": [
    {
      "source": "security@apache.org",
      "url": "https://lists.apache.org/thread/ohby1g6zjt72p0w79rhbr41nczzvr33y"
    },
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      "source": "af854a3a-2127-422b-91ae-364da2661108",
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  "sourceIdentifier": "security@apache.org",
  "vulnStatus": "Undergoing Analysis",
  "weaknesses": [
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      ],
      "source": "security@apache.org",
      "type": "Secondary"
    }
  ]
}

CVE-2026-84501 (GCVE-0-2026-84501)

Vulnerability from cvelistv5 – Published: 2026-09-16 09:28 – Updated: 2026-09-16 19:43

Title

Apache ZooKeeper: Operational log forgery via newline injection in EnsembleAuthenticationProvider

Summary

Severity

5.3 (Medium)


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

SSVC

Exploitation: none Automatable: yes Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-09-16 19:42 UTC

CWE

CWE-117 - Improper output neutralization for logs

Assigner

apache mitre root

References

2 references

URL	Tags
https://lists.apache.org/thread/ohby1g6zjt72p0w79…	vendor-advisory
http://www.openwall.com/lists/oss-security/2026/09/15/7

Impacted products

1 product

Vendor	Product	Version
Apache Software Foundation	Apache ZooKeeper	Affected: 3.9.0 , ≤ 3.9.5 (maven) Affected: 3.8.0 , ≤ 3.8.6 (maven)

Credits

Youlong Chen Institute of Computing Technology <chenyoulong20g@ict.ac.cn>

Show details on NVD website

JSON

To clipboard

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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.

Detection rules are retrieved from Rulezet.

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.

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.