# CVE-2026-87857: Temporal Server workflow-history pagination token is not bound to the requested namespace and workflow > CVE-2026-87857: Temporal Server workflow-history pagination token is not bound to the requested namespace and workflow. CVSS 5.3 (CVSS 4.0). Canonical: https://rewindex.com/cve/CVE-2026-87857 Last updated: 2026-11-09T20:18:14Z - Published: 2026-11-09 19:45 UTC · Updated: 2026-11-09 20:18 UTC · Assigner: Temporal - CVSS: 5.3 (CVSS 4.0) · Severity: Medium - EPSS: 0.40%, 34th percentile (scored 2026-11-10) - CISA KEV: no - CWE: CWE-639, CWE-863 ## Description Temporal Server does not bind a workflow-history pagination token to the namespace and workflow named in the request that presents it. GetWorkflowExecutionHistory and GetWorkflowExecutionHistoryReverse authorize the caller against the namespace in the request, then select history from the branch recorded inside the caller-supplied next\_page\_token. The normal history continuation carries a run identifier, event bounds, a persistence cursor, and a branch token, but no namespace or workflow identity, and it is serialized as unauthenticated protobuf bytes. An authenticated caller holding read permission on one namespace, together with a genuine non-final continuation issued earlier for a workflow in a second namespace, can submit that continuation with a request naming the first namespace and receive the second namespace's workflow history, provided the supplied workflow identifier selects the same History shard as the continuation's branch. No workflow with the supplied identifier needs to exist. Because the token is unauthenticated, a holder can also advance its event range and clear its persistence cursor, which returns history events created after that caller's current credential no longer granted access to the continuation's namespace. Determining exposure is a version question rather than a configuration question: every release listed as affected omits the binding check on the forward history path, and on the reverse history path in releases from 1.16.0, which introduced GetWorkflowExecutionHistoryReverse; no setting in an affected release restores it, and affected releases emit no metric or log for the condition, so their telemetry provides no detection. Fixed releases add the check and, when a page token's branch token is not the requested execution's current branch token, record the counter pagination\_token\_branch\_mismatch tagged with namespace and reason and write a History-service warning log reading "Pagination branch token is not the execution's current branch token" with the fields wf-namespace, wf-id, wf-run-id, reason, wf-branch-token, and wf-request-branch-token. Search History warning logs for that message, or for reason=foreign\_branch, which denotes a branch token the requested execution never recorded and is not expected in normal operation; reason=non\_current\_branch denotes a retained but superseded branch of the same execution and can occur legitimately after conflict resolution or failover. A foreign\_branch record does not by itself prove the read was refused, because the counter and log are emitted before the enforcement decision and therefore appear both when the check rejects the request and when history.enablePaginationTokenBranchValidationShadowMode is enabled and the read is served; confirm refusal from the gRPC response, which is InvalidArgument carrying a CurrentBranchChangedFailure detail. The metric and log are tagged with the requesting namespace, not the namespace whose history the token selects, so a foreign\_branch alert does not name the exposed namespace. The issue does not provide unauthenticated access, construction of a usable continuation from public workflow identifiers, enumeration of workflows for which the caller holds no continuation, or any modification of workflow state. ## Affected vendors and products - Temporal Technologies, Inc.: Temporal Server ## Tracked companies - [Temporal Cloud](https://rewindex.com/company/temporal-cloud.md) ## References - [CVE record on cve.org](https://www.cve.org/CVERecord?id=CVE-2026-87857) - [NVD entry](https://nvd.nist.gov/vuln/detail/CVE-2026-87857) - [https://github.com/temporalio/temporal/blob/v1.0.0/service/frontend/workflowHandler.go\#L602-L740](https://github.com/temporalio/temporal/blob/v1.0.0/service/frontend/workflowHandler.go#L602-L740) - [https://github.com/temporalio/temporal/commit/4b02728735450dd60eaff9a5d0dc8e11fc8a4b13](https://github.com/temporalio/temporal/commit/4b02728735450dd60eaff9a5d0dc8e11fc8a4b13) - [https://github.com/temporalio/temporal/commit/690b53103e11982de5f9187f722a0e0d3780028d](https://github.com/temporalio/temporal/commit/690b53103e11982de5f9187f722a0e0d3780028d) - [https://github.com/temporalio/temporal/commit/c82a2d228e7287b1d283a55477f40a1a48481010](https://github.com/temporalio/temporal/commit/c82a2d228e7287b1d283a55477f40a1a48481010) - [https://github.com/temporalio/temporal/commit/ceb1cc1071b1fd37f8a2cd8ef5ed3e4333245cc2](https://github.com/temporalio/temporal/commit/ceb1cc1071b1fd37f8a2cd8ef5ed3e4333245cc2) - [https://github.com/temporalio/temporal/pull/11723](https://github.com/temporalio/temporal/pull/11723) - [https://github.com/temporalio/temporal/pull/11919](https://github.com/temporalio/temporal/pull/11919) - [https://github.com/temporalio/temporal/pull/12039](https://github.com/temporalio/temporal/pull/12039) - [https://github.com/temporalio/temporal/pull/12040](https://github.com/temporalio/temporal/pull/12040) - [https://github.com/temporalio/temporal/releases/tag/v1.30.7](https://github.com/temporalio/temporal/releases/tag/v1.30.7) - [https://github.com/temporalio/temporal/releases/tag/v1.31.3](https://github.com/temporalio/temporal/releases/tag/v1.31.3) - [https://github.com/temporalio/temporal/releases/tag/v1.32.0](https://github.com/temporalio/temporal/releases/tag/v1.32.0) --- _Sources: CVE records from the CVE Program (cve.org). CVE® is a registered trademark of The MITRE Corporation. (https://www.cve.org/) This product uses data from the NVD API but is not endorsed or certified by the NVD. (https://nvd.nist.gov/) Known Exploited Vulnerabilities catalog from CISA. (https://www.cisa.gov/known-exploited-vulnerabilities-catalog) EPSS scores from FIRST (Exploit Prediction Scoring System). (https://www.first.org/epss/)_ --- Canonical: https://rewindex.com/cve/CVE-2026-87857 · Markdown: https://rewindex.com/cve/CVE-2026-87857.md · JSON: https://rewindex.com/api/v1/cves/CVE-2026-87857 · Data licensed CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/) · Generated 2026-11-11T04:21:49.853Z