Apache ZooKeeper: SASL authorization bypass on the client port through a client-supplied authorization ID
Affects Apache ZooKeeper 3.9.0 through 3.9.6 and 3.8.0 through 3.8.7 with SASL enabled on the client port. Fixed in 3.8.8 and 3.9.7.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
- Exploited
- No known exploitation
- Fix
- Fixed in 3.8.8, 3.9.7
- Who is exposed
- Specific setups only
Do first: Check whether your setup matches what the bug needs. SASL authentication is enabled on the client port Attacker's principal is not covered by the zookeeper.security.auth_to_local rules (with default rules, any Kerberos principal from a realm other than the server's default realm, such as a cross-realm trusted realm) Affected versions: Apache ZooKeeper 3.9.0 through 3.9.6 and 3.8.0 through 3.8.7
- Exploitation0/40No signal
- Exposure8/25Specific setups only, reachable over the network
- Reach10/20Affects Maven packages
- Severity9.6/10CVSS 8.6, total technical impact per CISA
- No patch0/5No signal
What would change the score
- Would score about 78 if added to CISA KEV
- Would score about 73 if CISA's SSVC rates exploitation active
- Would score about 35 if CISA's SSVC rates it automatable
CVE-2026-100252 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated CVSS 8.6 (high) and affects Apache ZooKeeper; fixed in 3.8.8 and 3.9.7.
- Last modified
- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean? →
- Published
- Whether CISA lists it in its Known Exploited Vulnerabilities catalog: proof that attackers are using it.What do these mean? →
- Not listed in CISA KEV
- A 0-100 score for how much a CVE matters across the industry: exploitation, exposure, how widely the software is used, severity and whether a fix exists.What do these mean? →
- 28/100 · provisional
- How many real-world setups can hit the bug, from the vendor's advisory and CISA data. It does not know your setup.What do these mean? →
- Specific setups only
- Fix
- Fixed in 3.8.8, 3.9.7
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
- Exploitation: none
- Automatable: no
- Technical impact: total
Summary
Apache ZooKeeper, when SASL authentication is enabled on the client port, lets a remote attacker who has a valid low-privilege login claim any SASL identity, including superuser access to the whole data tree if they request a configured superuser identity. This happens because the server accepts the client-requested identity without checking it against the authenticated principal, which is possible for principals not covered by the auth_to_local rules, such as Kerberos principals from other realms under the default rules.
Read the original description
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 any Kerberos principal from a realm other than the server's default realm, such as a principal from a cross-realm trusted realm. The client then gets the permissions granted to that identity in sasl ACLs. If the requested identity matches a configured zookeeper.superUser, it gets superuser access to the whole data tree. Users are recommended to upgrade to version 3.8.8 or 3.9.7, which fixes the issue.
Impact
- Widely used
175 packages depend on org.apache.zookeeper:zookeeper.Source: deps.dev
What to do
Check whether your setup matches what the bug needs.
SASL authentication is enabled on the client port Attacker's principal is not covered by the zookeeper.security.auth_to_local rules (with default rules, any Kerberos principal from a realm other than the server's default realm, such as a cross-realm trusted realm) Affected versions: Apache ZooKeeper 3.9.0 through 3.9.6 and 3.8.0 through 3.8.7Upgrade to a fixed version: 3.8.8, 3.9.7.
Timeline
- CVE published
- First seen by cve.now
- CISA SSVC assessment
Exploitation: none · Automatable: no · Technical impact: total
- Record last updated
Affected versions
- org.apache.zookeeper:zookeeperMaven
From 3.9.0 · through 3.9.6; From 3.8.0 · through 3.8.7
Evidence 2
- Advisory
- Link
Corrections
None so far.
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Questions about CVE-2026-100252
Is CVE-2026-100252 being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data
What does this mean?
An authenticated client can claim any SASL identity it names when its own principal is not covered by the zookeeper.security.auth_to_local rules. That identity receives the permissions granted in sasl ACLs, and if it matches a configured zookeeper.superUser, it gets superuser access to the whole data tree.Source: openwall.com
Which versions are affected by CVE-2026-100252?
org.apache.zookeeper:zookeeper (Maven): from 3.9.0 through 3.9.6; from 3.8.0 through 3.8.7.Source: cve.now feed data
Am I affected, and how do I check?
Apache ZooKeeper 3.9.0 through 3.9.6 and 3.8.0 through 3.8.7 are affected, but only when SASL authentication is enabled on the client port and the client's principal is not covered by auth_to_local rules. With the default rules, this includes Kerberos principals from a realm other than the server's default realm. Check the ZooKeeper version and the SASL and auth_to_local settings in the server configuration.Source: openwall.com
How do I fix CVE-2026-100252?
Upgrade to Apache ZooKeeper 3.8.8 or 3.9.7, which fix the issue.Source: openwall.com