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Highest advisory severityHigh 2 vendors · 2 advisories

CVE-2026-100252

Improper Authorization vulnerability in Apache ZooKeeper

CVE-2026-100252: Improper Authorization vulnerability in Apache ZooKeeper. Not in the CISA KEV catalog. High advisory severity (CVSS 8.6, Apache).

Compare the source-linked records below. Ratings and product/version details belong to each advisory; they are not a single CVE-wide score or proof that every listed product is affected. How VulniPulse collects and checks evidence.

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CVE-2026-100252 key facts

CISA KEV
Not listed (catalog checked )
Highest advisory severity
High
CVSS base score
8.6 (Apache), 8.1 (Red Hat)
Weakness
CWE-807
Fixed releases
  • Apache: 3.8.8, 3.9.7
Vendor advisories
2 from Apache, Red Hat
VulniPulse record
Published · Updated

Scores, vectors, weaknesses and fixed releases are quoted from vendor advisories that cover only CVE-2026-100252; bulletin-wide values are not repeated here.

Is CVE-2026-100252 exploited?

No exploitation is reported in the sources VulniPulse tracks: CVE-2026-100252 is not in the CISA KEV catalog (checked ) and no tracked advisory for it reports exploitation. That is not proof the vulnerability cannot be exploited.

How do I fix CVE-2026-100252?

Upgrade to a fixed release named by the vendor:

  • Apache: 3.8.8, 3.9.7
  • The server then tries to replace the requested identity with a canonical form of the authenticated principal, derived from the zookeeper.security.auth_to_local rules. (Apache)
  • Users are recommended to upgrade to version 3.8.8 or 3.9.7, which fixes the issue. (Apache)
  • 1. Network Access Control: Restrict network reachability to the ZooKeeper client port (default TCP 2181) so that only trusted client nodes and application services can connect. On Red Hat Enterprise Linux systems running firewalld, restrict access to a dedicated trusted zone: firewall-cmd --zone=trusted --add-source= --permanent firewall-cmd --zone=trusted --add-port=2181/tcp --permanent firewall-cmd --reload Warning: Reloading firewalld applies new firewall rules immediately and can disrupt active network sessions if misconfigured. 2. Configuration Hardening: Explicitly configure 'zookeeper.security.auth_to_local' mapping rules in zoo.cfg to handle all legitimate Kerberos realms and principals, ensuring that canonicalization succeeds for all accepted accounts rather than failing open. Caveats: Network restriction reduces the attack surface from untrusted networks but does not prevent abuse from authenticated clients on authorized networks if cross-realm principals remain unmapped. (Red Hat)

Vendor advisory comparison

Apache

1 advisory
  • Advisory severityHigh8.6

    High [CVE-2026-100252] Improper Authorization vulnerability in Apache ZooKeeper

    CVE-2026-100252Source published Source updated

    Improper Authorization vulnerability in Apache ZooKeeper. When SASL authentication is enabled on the client port, the server's SASL callback handler grants every authorization identity (authzid) that a client requests, without checking it against the principal the client authenticated as. The server then tries to replace the requested identity with a canonical form of the authenticated principal, derived from the zookeeper.security.auth_to_local rules. If no rule applies to the principal, canonicalization fails and the error is only logged. The client-requested authzid then becomes the session's SASL identity for all ACL checks. An authenticated client whose principal is not covered by the auth_to_local rules can therefore claim any SASL identity. With the default rules, this includes…

    Affected products in this advisory
    • Apache ZooKeeper
    Source-reported affected versions
    • Apache ZooKeeper 3.9.0 through 3.9.6
    • Apache ZooKeeper 3.8.0 through 3.8.7
    Source-reported fixed versions
    • 3.8.8
    • 3.9.7
    Mitigation guidance
    • The server then tries to replace the requested identity with a canonical form of the authenticated principal, derived from the zookeeper.security.auth_to_local rules.
    • Users are recommended to upgrade to version 3.8.8 or 3.9.7, which fixes the issue.
    Full advisory and evidenceOpen source bulletin

Red Hat

1 advisory
  • Advisory severityHigh8.1

    High [CVE-2026-100252] Privilege escalation via improper SASL authorization identity validation

    CVE-2026-100252Source published Source updated

    Privilege escalation via improper SASL authorization identity validation. Red Hat rates this important (CVSS 8.1). Weakness: CWE-807. Affected products named by the advisory: Red Hat AMQ Broker 7; Red Hat Fuse 7; Red Hat Offline Knowledge Portal; Red Hat OpenShift AI (RHOAI).

    Related products — impact not confirmed
    • Red Hat AMQ Broker 7
    • Red Hat Fuse 7
    • Red Hat Offline Knowledge Portal
    • Red Hat OpenShift AI (RHOAI)
    Source-reported affected versions
    Affected-version details not available in this record.
    Source-reported fixed versions
    No fixed-version detail extracted. This does not mean no fix exists.
    Mitigation guidance
    • 1. Network Access Control: Restrict network reachability to the ZooKeeper client port (default TCP 2181) so that only trusted client nodes and application services can connect. On Red Hat Enterprise Linux systems running firewalld, restrict access to a dedicated trusted zone: firewall-cmd --zone=trusted --add-source=<TRUSTED_IP_OR_SUBNET> --permanent firewall-cmd --zone=trusted --add-port=2181/tcp --permanent firewall-cmd --reload Warning: Reloading firewalld applies new firewall rules immediately and can disrupt active network sessions if misconfigured. 2. Configuration Hardening: Explicitly configure 'zookeeper.security.auth_to_local' mapping rules in zoo.cfg to handle all legitimate Kerberos realms and principals, ensuring that canonicalization succeeds for all accepted accounts rather than failing open. Caveats: Network restriction reduces the attack surface from untrusted networks but does not prevent abuse from authenticated clients on authorized networks if cross-realm principals remain unmapped.
    Full advisory and evidenceOpen source bulletin

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