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VulnerabilityPublished Updated

CVE-2026-24281: Apache ZooKeeper · Reliance on Reverse DNS Resolution for a Security-Critical Action

Affects Apache ZooKeeperSource CVE Database V5

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Not known to be exploited · CVSS 5.9 Medium : upgrade to 3.9.5 or 3.8.6 when convenient.

Data as of 30 Oct 2026, 11:52 UTC

CVSS 3.1 base score
5.9Medium
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.6% chance of exploitation in 30 days – higher than 50% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 3.9.5, 3.8.6
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 7 Mar 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.

What to do

Upgrade org.apache.zookeeper/zookeeper to 3.9.5 or 3.8.6.

Affected software

ProductAffectedFixed in
Apache Software FoundationApache ZooKeeperAffected
  • >=3.9.0 <=3.9.4
  • >=3.8.0 <=3.8.5
Fixed in–
Mavenorg.apache.zookeeper/zookeeperpkg:maven/org.apache.zookeeper/zookeeperOther threatsAffected
  • <3.8.6
  • >=3.8.0 <3.8.6
  • <3.9.5
  • >=3.9.0 <3.9.5
Fixed in
  • 3.8.6
  • 3.9.5
MavenApache Software Foundation/org.apache.zookeeper:zookeeperpkg:maven/Apache Software Foundation/org.apache.zookeeper:zookeeperOther threatsAffected
  • >=3.9.0 <=3.9.4
  • >=3.8.0 <=3.8.5
Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

A fix is available by upgrading Apache ZooKeeper to versions 3.8.6 or 3.9.5, which add a configuration option to disable reverse DNS lookup in client and quorum protocols, thereby preventing reliance on potentially spoofed PTR records. Users should apply these updates to remediate the vulnerability. No other vendor advisories indicate alternative mitigations or that no action is required.

Description

Hostname verification in Apache ZooKeeper ZKTrustManager falls back to reverse DNS (PTR) when IP SAN validation fails, allowing attackers who control or spoof PTR records to impersonate ZooKeeper servers or clients with a valid certificate for the PTR name. It's important to note that attacker must present a certificate which is trusted by ZKTrustManager which makes the attack vector harder to exploit. Users are recommended to upgrade to version 3.8.6 or 3.9.5, which fixes this issue by introducing a new configuration option to disable reverse DNS lookup in client and quorum protocols.

References

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