CVE-2026-105935 — Apache Pulsar: Function trigger publishes to the input topic without checking the caller's produce permission
The Pulsar Functions Worker provides a REST API endpoint for triggering a function, which publishes a caller-supplied value to one of the function's configured input topics. The Functions Worker performs this publish with its own broker client, which authenticates with the Worker's configured broker-client credentials rather than the credentials of the API caller. When authorization is enabled, in Apache Pulsar 2.4.0 and later versions, the trigger endpoint checks only that the caller is authorized to perform function operations in the function's namespace. It does not check that the caller is authorized to produce to the input topic that the message is published to. Versions before 2.4.0 do not perform a caller authorization check for the trigger endpoint at all. Function input topics are not restricted to the function's own tenant or namespace, and registering a function does not require produce permission on its input topics. As a result, an authenticated user who is authorized to manage functions in a namespace, for example a role granted the functions permission on that namespace, can cause the Functions Worker to publish messages with caller-controlled content to a topic that the user is not authorized to produce to, including topics in other tenants. These messages are published under the identity of the Functions Worker. The issue does not require any function instance to be running or any function code to be executed. It requires that the Functions Worker's broker-client identity is itself authorized to produce to the target topic and, in Apache Pulsar 2.3.0 and later versions, to list the subscriptions of the target topic, as is the case when that identity is a superuser. The impact is on the integrity of the data in the affected topics: consumers of those topics may receive messages from a user who is not permitted to publish them. This concerns the Functions Worker REST API as called by an external, authenticated client; it does not change the security model for function code, which must be fully trusted. In fixed versions, when authorization is enabled, triggering a function additionally requires the caller to be authorized to produce to the selected input topic before any message is published. This issue affects Apache Pulsar versions from 2.0.0-rc1-incubating 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/. Users of Apache Pulsar 2.4.0 and later versions with authorization enabled who cannot upgrade immediately can limit the permission to manage functions to trusted roles. Users of versions before 2.4.0 should restrict access to the Functions Worker REST API to trusted callers, because in these versions the trigger endpoint does not check the caller's permission to manage functions.
Who exploits it and how urgent it is
A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.
How the score was calculated
- EPSS 0.4% (30-day exploitation probability)+5
- Technical severity (medium)+3
The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).
Triage
Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.
CISA SSVC assessment CISA
Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.
Remediation
Fixes and mitigations documented by the sources — linked to the original advisory.
No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.
First 24 hours
Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.
- Identify exposed assets running the affected vendor/product/version combinations (Apache Software Foundation Apache Pulsar).
- No fix documented in the sources: reduce exposure and monitor the vendor advisory.
- Search available logs for exploit probes matching the vulnerability class (access control), errors and authentication anomalies.
Affected scope
Vendor, product and versions as the sources word them.
| Vendor | Product | Versions | Status | Source |
|---|---|---|---|---|
| Apache Software Foundation | Apache Pulsar | ≥ 2.0.0-rc1-incubating and < 4.0.14≥ 4.1.0 and < 4.2.5 | Vulnerable | CVE Program (cve.org) e CISA ADP |
Attack characteristics
The CVSS vector, decoded. It describes the attack, not your exposure to it.
Every base score collected
Sources score independently and may disagree; each row says who scored it and under which version.
| Score | Version | Severity | Expl. | Impact | Scored by |
|---|---|---|---|---|---|
| 4.9 | CVSS 4.0 | Medium | — | — | security@apache.org via NIST National Vulnerability Database |
| 4.9 | CVSS 4.0 | Medium | — | — | apache via CVE Program (cve.org) e CISA ADP |
CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:N/SC:N/SI:H/SA:N/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 (score shown at the top: security@apache.org) Weakness MITRE
Weakness class according to MITRE’s CWE catalog.
EPSS over time FIRST
Oct 22, 2026 → Oct 30, 2026 · 9 reading(s) · max 0.40%
Detection
Read off the CVSS vector and the weakness class. Starting points, not tested rules.
- Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
- Audit administrative actions and access to resources outside each user’s normal pattern.
Timeline
What happened to this CVE, newest first.
- 2026
- SSVC assessment updated
- Source status changed · Received → Awaiting Analysis
- Source status changed · Published → Received
- Record published
- CVSS changed · 4.9
- Source status changed · → Published
- Record created in this database
- CVE published
Source activity
Repeated readings are counted rather than listed.
- 1× References added · Oct 22, 2026 – Oct 22, 2026
- 1× Official description updated · Oct 21, 2026 – Oct 21, 2026
References
5 on the record
Elsewhere on this site
Related CVEs (same products)
- High CVE-2026-105942 Apache Pulsar: Original principal of proxied requests authorized with the proxy's authentication data, allowing privilege escalation 10d
- High CVE-2026-105945 Apache Pulsar: Improper Validation of Package Name Components Allows Cross-Tenant Package Access in Filesystem Package Storage 10d
- High CVE-2026-105934 Apache Pulsar: Missing tenant admin authorization check when truncating a partitioned topic 10d
- Medium CVE-2026-105936 Apache Pulsar: Functions connectors list endpoint does not apply the super-user check of the worker connectors endpoint 10d
- High CVE-2026-105937 Apache Pulsar: Missing authorization of the shadow topic source allows cross-tenant message disclosure and deletion of source topic data 10d
- Low CVE-2026-105938 Apache Pulsar: Subscription authorization policies not enforced by namespace-level backlog and unsubscribe operations and by topic expire-all 10d
Not in any source we poll
Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.
- No fixed version, patch or mitigation documented.
- No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
- No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
- No exploit packet captures, log samples, or incident case IDs supplied.
Answered from this record
Text assembled only from the fields above — no additional claims.
What should defenders know first?
CVE-2026-105935 is "Apache Pulsar: Function trigger publishes to the input topic without checking the caller's produce permission", rated Medium. It affects Apache Pulsar (Apache Software Foundation); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 4.9 describes technical severity. EPSS 0.40% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.
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