CVE-2026-105942 (GCVE-0-2026-105942)
Vulnerability from cvelistv5 – Published: 2026-10-21 18:14 – Updated: 2026-10-23 21:58
VLAI
EPSS
VEX
Title
Apache Pulsar: Original principal of proxied requests authorized with the proxy's authentication data, allowing privilege escalation
Summary
When a configured proxy role sends a request to the broker on behalf of another user (the original principal), the broker is designed to authorize both the proxy role and the original principal and to allow the request only if both are authorized, so that the original principal cannot exceed its own permissions. Two flaws weakened this check.
First, the original principal was authorized with the proxy's authentication data instead of its own. On the admin REST API of the broker and the functions worker, this applied to every proxied request. On the Pulsar binary protocol, it applied when the proxy did not forward the client's credentials to the broker, which was the default of the Pulsar proxy in the affected versions. Authorization providers that resolve permissions from the role name only, such as the default authorization provider, are not affected by this flaw. The multi-role token authorization provider (MultiRolesTokenAuthorizationProvider), added in Apache Pulsar 2.8.1, resolves roles from the role claim of the token in the authentication data it is given. When a proxy authenticates to the broker with its own token, the original principal was therefore authorized with all roles in the proxy's token. If any of those roles is a superuser or tenant admin role, any user whose requests are forwarded by that proxy can perform operations that need those permissions without holding them. Custom authorization providers that use the authentication data could be affected in a similar way.
Second, independently of the authorization provider, the tenant admin check of a proxied admin REST API request succeeded without checking the original principal when the proxy role was itself an admin role of the tenant. In deployments where a proxy role is a tenant admin, including with the default authorization provider, any user whose requests are forwarded by that proxy could perform tenant administration operations on that tenant. This behavior is present from 2.8.4 in the 2.8.x releases, from 2.9.3 in the 2.9.x releases, and from 2.10.1 onwards.
Deployments that use neither the multi-role token authorization provider nor a custom provider that uses the authentication data are not affected by the first flaw, and with the multi-role token authorization provider, neither are deployments whose proxies do not authenticate to the broker with a token. Deployments in which no proxy role is listed as an admin role of a tenant are not affected by the second flaw. A proxy role that is a superuser but is not listed as a tenant admin does not trigger it, because the tenant admin check of the built-in authorization providers only considers the tenant's admin roles; this can differ for custom authorization providers that treat superusers as tenant admins.
In fixed versions, both the proxy role and the original principal are authorized for each proxied request, and the original principal is authorized only with its own authentication data. With the multi-role token authorization provider, the roles of a forwarded token are used for the original principal only when that token authenticates as the original principal; otherwise only the original principal's role name is used. For tenant admin checks, the proxy role and the original principal must each be a superuser or a tenant admin of the tenant.
This issue affects Apache Pulsar versions from 2.8.1 before 4.0.14 and from 4.1.0 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/.
Severity
SSVC
Exploitation: none
Automatable: no
Technical Impact: total
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-10-23 20:45 UTC
CWE
- CWE-863 - Incorrect Authorization
Assigner
References
2 references
| URL | Tags |
|---|---|
| https://pulsar.apache.org/security/CVE-2026-105942/ | vendor-advisory |
| https://lists.apache.org/thread.html/4jmsbztr1fww… | vendor-advisory |
Impacted products
1 product
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| Apache Software Foundation | Apache Pulsar |
Affected:
2.8.1 , < 4.0.14
(semver)
Affected: 4.1.0 , < 4.2.5 (semver) |
guessed |
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"value": "When a configured proxy role sends a request to the broker on behalf of another user (the original principal), the broker is designed to authorize both the proxy role and the original principal and to allow the request only if both are authorized, so that the original principal cannot exceed its own permissions. Two flaws weakened this check.\n\nFirst, the original principal was authorized with the proxy\u0027s authentication data instead of its own. On the admin REST API of the broker and the functions worker, this applied to every proxied request. On the Pulsar binary protocol, it applied when the proxy did not forward the client\u0027s credentials to the broker, which was the default of the Pulsar proxy in the affected versions. Authorization providers that resolve permissions from the role name only, such as the default authorization provider, are not affected by this flaw. The multi-role token authorization provider (MultiRolesTokenAuthorizationProvider), added in Apache Pulsar 2.8.1, resolves roles from the role claim of the token in the authentication data it is given. When a proxy authenticates to the broker with its own token, the original principal was therefore authorized with all roles in the proxy\u0027s token. If any of those roles is a superuser or tenant admin role, any user whose requests are forwarded by that proxy can perform operations that need those permissions without holding them. Custom authorization providers that use the authentication data could be affected in a similar way.\n\nSecond, independently of the authorization provider, the tenant admin check of a proxied admin REST API request succeeded without checking the original principal when the proxy role was itself an admin role of the tenant. In deployments where a proxy role is a tenant admin, including with the default authorization provider, any user whose requests are forwarded by that proxy could perform tenant administration operations on that tenant. This behavior is present from 2.8.4 in the 2.8.x releases, from 2.9.3 in the 2.9.x releases, and from 2.10.1 onwards.\n\nDeployments that use neither the multi-role token authorization provider nor a custom provider that uses the authentication data are not affected by the first flaw, and with the multi-role token authorization provider, neither are deployments whose proxies do not authenticate to the broker with a token. Deployments in which no proxy role is listed as an admin role of a tenant are not affected by the second flaw. A proxy role that is a superuser but is not listed as a tenant admin does not trigger it, because the tenant admin check of the built-in authorization providers only considers the tenant\u0027s admin roles; this can differ for custom authorization providers that treat superusers as tenant admins.\n\nIn fixed versions, both the proxy role and the original principal are authorized for each proxied request, and the original principal is authorized only with its own authentication data. With the multi-role token authorization provider, the roles of a forwarded token are used for the original principal only when that token authenticates as the original principal; otherwise only the original principal\u0027s role name is used. For tenant admin checks, the proxy role and the original principal must each be a superuser or a tenant admin of the tenant.\n\nThis issue affects Apache Pulsar versions from 2.8.1 before 4.0.14 and from 4.1.0 before 4.2.5.\n\n- 4.0.x version users should upgrade to at least 4.0.14.\n- 4.1.x and 4.2.x version users should upgrade to at least 4.2.5.\n\nUsers operating versions prior to those listed above should upgrade to the aforementioned patched versions or newer versions.\n\nThe 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/."
}
],
"metrics": [
{
"cvssV4_0": {
"Automatable": "NOT_DEFINED",
"Recovery": "NOT_DEFINED",
"Safety": "NOT_DEFINED",
"attackComplexity": "LOW",
"attackRequirements": "PRESENT",
"attackVector": "NETWORK",
"baseScore": 7.7,
"baseSeverity": "HIGH",
"exploitMaturity": "NOT_DEFINED",
"privilegesRequired": "LOW",
"providerUrgency": "NOT_DEFINED",
"subAvailabilityImpact": "NONE",
"subConfidentialityImpact": "NONE",
"subIntegrityImpact": "NONE",
"userInteraction": "NONE",
"valueDensity": "NOT_DEFINED",
"vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N",
"version": "4.0",
"vulnAvailabilityImpact": "HIGH",
"vulnConfidentialityImpact": "HIGH",
"vulnIntegrityImpact": "HIGH",
"vulnerabilityResponseEffort": "NOT_DEFINED"
},
"format": "CVSS",
"scenarios": [
{
"lang": "en",
"value": "GENERAL"
}
]
}
],
"problemTypes": [
{
"descriptions": [
{
"cweId": "CWE-863",
"description": "CWE-863 Incorrect Authorization",
"lang": "en",
"type": "CWE"
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-10-21T18:14:35.996Z",
"orgId": "f0158376-9dc2-43b6-827c-5f631a4d8d09",
"shortName": "apache"
},
"references": [
{
"tags": [
"vendor-advisory"
],
"url": "https://pulsar.apache.org/security/CVE-2026-105942/"
},
{
"tags": [
"vendor-advisory"
],
"url": "https://lists.apache.org/thread.html/4jmsbztr1fwws5fmxk36q5326wvjlwx4"
}
],
"source": {
"discovery": "INTERNAL"
},
"title": "Apache Pulsar: Original principal of proxied requests authorized with the proxy\u0027s authentication data, allowing privilege escalation",
"x_generator": {
"engine": "Vulnogram 1.0.3"
}
}
},
"cveMetadata": {
"assignerOrgId": "f0158376-9dc2-43b6-827c-5f631a4d8d09",
"assignerShortName": "apache",
"cveId": "CVE-2026-105942",
"datePublished": "2026-10-21T18:14:35.996Z",
"dateReserved": "2026-10-06T07:05:02.164Z",
"dateUpdated": "2026-10-23T21:58:05.657Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
}
}
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Drag nodes to arrange them. Double-click a related vulnerability to open it, or a source to visit its link. The Physics button on the left tunes the layout and the simulation; the legend at the bottom left hides or shows nodes by kind and by sighting type.
Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
Vulnerability timeline
Sightings and recorded dates, grouped by day · UTC
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.