CVE-2026-84501
mediumpriority · track · 0EPSS 0.007 · 54 %ileDEUSEPSS · scored 2026-10-27
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.
cvss
Technical severity, 0–10. One row per scoring source.
base score 0–10 · higher = more severe · hover a vector to decode
ssvc
A stakeholder decision — act, attend, or track — from exploitation and impact.
weaknesses
The CWE weakness classes this flaw belongs to.
affected products (14)
Products and version ranges known to be affected.
- Construction and Engineeringall versionscert_bundDEcpe:/a:oracle:construction_and_engineering:21.12.0-21.12.17
- Construction and Engineeringall versionscert_bundDEcpe:/a:oracle:construction_and_engineering:21.12.0-21.12.18
- Construction and Engineeringall versionscert_bundDEcpe:/a:oracle:construction_and_engineering:21.12.0.0-21.12.21.9
- Construction and Engineeringall versionscert_bundDEcpe:/a:oracle:construction_and_engineering:22.12.0-22.12.15
- Construction and Engineeringall versionscert_bundDEcpe:/a:oracle:construction_and_engineering:22.12.0.0-22.12.21.4
- Construction and Engineeringall versionscert_bundDEcpe:/a:oracle:construction_and_engineering:23.12.0-23.12.16
- Construction and Engineeringall versionscert_bundDEcpe:/a:oracle:construction_and_engineering:23.12.0-23.12.20
- Construction and Engineeringall versionscert_bundDEcpe:/a:oracle:construction_and_engineering:24.12.0-24.12.16
- Construction and Engineeringall versionscert_bundDEcpe:/a:oracle:construction_and_engineering:25.12.0-25.12.8
- Construction and Engineeringall versionscert_bundDEcpe:/a:oracle:construction_and_engineering:25.12.0-25.12.9
advisories (2)
Vendor and ecosystem advisories describing this.
- WID-SEC-W-2026-4089Oracle Construction and Engineering: Mehrere SchwachstellenDeutsch2026-10-20csaf · cert_bundDE
Ein entfernter, anonymer oder authentisierter Angreifer kann mehrere Schwachstellen in Oracle Construction and Engineering ausnutzen, um die Vertraulichkeit, Integrität und Verfügbarkeit zu gefährden.
- BIT-zookeeper-2026-84501Apache ZooKeeper: Operational log forgery via newline injection in EnsembleAuthenticationProvider2026-09-19vendor · osvUS
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.
sources
Which sources assert this record, and when.
references (2) nvd
External citations — patches, advisories, analysis.
- http://www.openwall.com/lists/oss-security/2026/09/15/7Mailing List
- https://lists.apache.org/thread/ohby1g6zjt72p0w79rhbr41nczzvr33yMailing ListVendor Advisory
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