Apache Pulsar: Missing Topic Authorization on Binary Protocol GetSchema and GetOrCreateSchema Commands

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-105926
StatePUBLISHED
Assignerapache
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-10-21 18:17:22 UTC
Updated2026-10-30 19:18:01 UTC
DescriptionThe Pulsar broker serves two schema commands on its binary protocol: GetSchema, which returns the schema registered for a topic, and GetOrCreateSchema, which registers a new schema version for an existing topic. The broker handled both commands after checking only that the client connection was authenticated. Unlike the broker's other topic commands, such as those for creating producers and consumers or for looking up topics, these two commands did not check whether the authenticated client was authorized for the target topic. The Pulsar REST API endpoints for schemas were not affected. An authenticated client without any permission on the target topic, namespace or tenant could use these commands to: - read the schema registered for a topic in another namespace or tenant, disclosing the schema definition such as record field names and types. Message payloads are not disclosed. - register a new schema version on an existing topic in another namespace or tenant. The topic's schema compatibility and schema auto-update policies still apply. The issue does not allow message data to be read or modified, but a registered schema version can cause legitimate producers and consumers of that topic to fail with schema incompatibility errors until the schema is corrected by an administrator. The standard Pulsar client performs an authorized topic lookup before it sends these commands, so the missing check could not be observed when testing with the standard client. A client that implements the binary protocol directly is not required to perform that lookup first. This issue is relevant only to deployments that have authentication and authorization enabled. The GetSchema command is affected from Apache Pulsar 2.2.0, and the GetOrCreateSchema command from Apache Pulsar 2.5.0. After the fix, the broker requires the lookup permission on the topic for GetSchema and the produce permission on the topic for GetOrCreateSchema. This impact analysis assumes that Pulsar has been configured with the default authorization provider. For custom authorization providers, the impact could be slightly different. This issue affects Apache Pulsar versions from 2.2.0 before 4.0.14, from 4.1.0 through 4.1.3, and from 4.2.0 before 4.2.5. - 4.0.x version users should upgrade to at least 4.0.14. - 4.1.x and 4.2.x version users should upgrade to at least 4.2.5. Users operating versions prior to those listed above should upgrade to the aforementioned patched versions or newer versions. The currently supported Apache Pulsar release lines are 4.0.x and 5.0.x. The supported versions schedule is available at https://pulsar.apache.org/contribute/release-policy/.

Risk And Classification

Primary CVSS: v4.0 5.3 MEDIUM from [email protected]

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:L/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

EPSS: 0.004080000 probability, percentile 0.350350000 (date 2026-11-02)

Problem Types: CWE-862 | CWE-862 CWE-862 Missing Authorization

VersionSourceTypeScoreSeverityVector
4.0[email protected]Secondary5.3MEDIUMCVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:L/E:X/C...
4.0CNACVSS5.3MEDIUMCVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:L

CVSS v4.0 Breakdown

Attack Vector
Network
Attack Complexity
Low
Attack Requirements
None
Privileges Required
Low
User Interaction
None
Confidentiality
Low
Integrity
Low
Availability
Low
Sub Conf.
None
Sub Integrity
None
Sub Availability
Low

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:L/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Apache Software Foundation Apache Pulsar affected 2.2.0 4.0.14 semver Not specified
CNA Apache Software Foundation Apache Pulsar affected 4.1.0 4.1.3 semver Not specified
CNA Apache Software Foundation Apache Pulsar affected 4.2.0 4.2.5 semver Not specified

References

ReferenceSourceLinkTags
pulsar.apache.org/security/CVE-2026-105926 [email protected] pulsar.apache.org
lists.apache.org/thread.html/45y22fqoqyfpc2hdmoct8cmgslz8ogkh [email protected] lists.apache.org
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: Claude and Ada Logics (en)

CNA: n0mi1k (en)

CNA: MopMonk-AI (en)

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