Vulnerability-Lookup

FKIE_CVE-2026-84439

Vulnerability from fkie_nvd - Published: 2026-09-16 10:16 - Updated: 2026-09-17 20:18

Severity

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

Summary

When audit logging is enabled (zookeeper.audit.enable=true), an unauthenticated attacker can inject arbitrary fields into Apache ZooKeeper's audit log by sending a digest authentication request with tab characters (\t) embedded in the username. Because the audit log uses tab-separated key=value format, the injected tabs are parsed as legitimate field separators, allowing the attacker to spoof audit results (e.g., injecting result=success), forge operation types, and corrupt forensic evidence. A log injection vulnerability in Apache ZooKeeper allows a client that can call setACL to inject forged key-value fields into zookeeper_audit.log. When audit logging is enabled, the server serializes attacker-controlled digest ACL ids into the acl= audit field without escaping tab characters. Because audit events are emitted as tab-separated key=value records, a crafted ACL id can make one successful setAcl event appear to contain forged fields such as operation=delete and znode=/forged. This undermines the integrity of downstream audit parsing, alerting, and incident response. 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 3.9.6 or 3.8.7, which fixes the issue.

References

	URL	Tags
	security@apache.org	https://lists.apache.org/thread/b7qnjvqjh393l0j07tmnb5ggg40sx3m6
	af854a3a-2127-422b-91ae-364da2661108	http://www.openwall.com/lists/oss-security/2026/09/15/6

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": [
            {
              "lessThanOrEqual": "3.9.5",
              "status": "affected",
              "version": "3.9.0",
              "versionType": "maven"
            },
            {
              "lessThanOrEqual": "3.8.6",
              "status": "affected",
              "version": "3.8.0",
              "versionType": "maven"
            }
          ]
        }
      ],
      "source": "security@apache.org"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "When audit logging is enabled (zookeeper.audit.enable=true), an unauthenticated attacker can inject arbitrary fields into Apache ZooKeeper\u0027s audit log by sending a digest authentication request with tab characters (\\t) embedded in the username. Because the audit log uses tab-separated\u00a0key=value\u00a0format, the injected tabs are parsed as legitimate field separators, allowing the attacker to spoof audit results (e.g., injecting\u00a0result=success), forge operation types, and corrupt forensic evidence.\n\nA log injection vulnerability in Apache ZooKeeper allows a client that can call\u00a0setACL\u00a0to inject forged key-value fields into\u00a0zookeeper_audit.log. When audit logging is enabled, the server serializes attacker-controlled digest ACL ids into the\u00a0acl=\u00a0audit field without escaping tab characters. Because audit events are emitted as tab-separated\u00a0key=value\u00a0records, a crafted ACL id can make one successful\u00a0setAcl\u00a0event appear to contain forged fields such as\u00a0operation=delete\u00a0and\u00a0znode=/forged. This undermines the integrity of downstream audit parsing, alerting, and incident response.\n\nThis issue affects Apache ZooKeeper: from 3.9.0 through 3.9.5, from 3.8.0 through 3.8.6.\n\nUsers are recommended to upgrade to version 3.9.6 or 3.8.7, which fixes the issue."
    }
  ],
  "id": "CVE-2026-84439",
  "lastModified": "2026-09-17T20:18:48.187",
  "metrics": {
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          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "NONE",
          "baseScore": 5.3,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "NONE",
          "integrityImpact": "LOW",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N",
          "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": "2026-09-17T19:14:36.442526Z",
          "version": "2.0.3"
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  },
  "published": "2026-09-16T10:16:53.433",
  "references": [
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      "source": "security@apache.org",
      "url": "https://lists.apache.org/thread/b7qnjvqjh393l0j07tmnb5ggg40sx3m6"
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    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "url": "http://www.openwall.com/lists/oss-security/2026/09/15/6"
    }
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  "sourceIdentifier": "security@apache.org",
  "vulnStatus": "Undergoing Analysis",
  "weaknesses": [
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        {
          "lang": "en",
          "value": "CWE-117"
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      ],
      "source": "security@apache.org",
      "type": "Secondary"
    }
  ]
}

CVE-2026-84439 (GCVE-0-2026-84439)

Vulnerability from cvelistv5 – Published: 2026-09-16 09:27 – Updated: 2026-09-17 19:14

Title

Apache ZooKeeper: Audit log injection via unsanitized output from multiple sources

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 2026-09-17 19:14 UTC

CWE

CWE-117 - Improper output neutralization for logs

Assigner

apache mitre root

References

2 references

URL	Tags
https://lists.apache.org/thread/b7qnjvqjh393l0j07…	vendor-advisory
http://www.openwall.com/lists/oss-security/2026/09/15/6

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.