Temporal Server workflow-history pagination token is not bound to the requested namespace and workflow
Summary
| CVE | CVE-2026-87857 |
|---|---|
| State | PUBLISHED |
| Assigner | Temporal |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-11-09 20:18:14 UTC |
| Updated | 2026-11-09 20:18:14 UTC |
| 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. |
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:N/VA:N/SC:N/SI:N/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
Problem Types: CWE-639 | CWE-863 | CWE-639 CWE-639: Authorization Bypass Through User-Controlled Key | CWE-863 CWE-863: Incorrect Authorization
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 4.0 | [email protected] | Secondary | 5.3 | MEDIUM | CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/C... |
| 4.0 | CNA | CVSS | 5.3 | MEDIUM | CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N |
CVSS v4.0 Breakdown
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/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
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Temporal Technologies Inc. | Temporal Server | unknown 0.0.0 1.0.0 semver | Not specified |
| CNA | Temporal Technologies Inc. | Temporal Server | affected 1.0.0 1.29.7 semver | Not specified |
| CNA | Temporal Technologies Inc. | Temporal Server | affected 1.30.0 1.30.7 semver | Not specified |
| CNA | Temporal Technologies Inc. | Temporal Server | affected 1.31.0 1.31.3 semver | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| github.com/temporalio/temporal/pull/12039 | [email protected] | github.com | |
| github.com/temporalio/temporal/releases/tag/v1.31.3 | [email protected] | github.com | |
| github.com/temporalio/temporal/pull/12040 | [email protected] | github.com | |
| github.com/temporalio/temporal/commit/4b02728735450dd60eaff9a5d0dc8e11fc... | [email protected] | github.com | |
| github.com/temporalio/temporal/pull/11919 | [email protected] | github.com | |
| github.com/temporalio/temporal/commit/690b53103e11982de5f9187f722a0e0d37... | [email protected] | github.com | |
| github.com/temporalio/temporal/releases/tag/v1.32.0 | [email protected] | github.com | |
| github.com/temporalio/temporal/commit/ceb1cc1071b1fd37f8a2cd8ef5ed3e4333... | [email protected] | github.com | |
| github.com/temporalio/temporal/commit/c82a2d228e7287b1d283a55477f40a1a48... | [email protected] | github.com | |
| github.com/temporalio/temporal/pull/11723 | [email protected] | github.com | |
| github.com/temporalio/temporal/releases/tag/v1.30.7 | [email protected] | github.com | |
| github.com/temporalio/temporal/blob/v1.0.0/service/frontend/workflowHand... | [email protected] | github.com | |
| 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: Reported internally at Temporal Technologies, Inc. (en)
Additional Advisory Data
Solutions
CNA: Upgrade to Temporal Server 1.30.7, 1.31.3, or 1.32.0, as appropriate for the deployed minor release line, and leave history.enablePaginationTokenBranchValidation at its default of true and history.enablePaginationTokenBranchValidationShadowMode at its default of false. The fix loads mutable state for the namespace and workflow named in the authorized request together with the run identifier from the page token, requires the token's branch token to equal that execution's current branch token, and rejects the request before any history persistence read. It covers the forward decoded, forward raw, and reverse history paths; the forward long-poll refresh path independently replaces the caller's branch token with the authorized execution's current branch token before reading history. Temporal Server releases up to and including 1.29.7 are outside the supported window and receive no fix; operators on those releases should upgrade to a supported line.
Workarounds
CNA: No setting in an affected release closes this issue, because the binding check does not exist there. Until upgrading, limit exposure by granting namespace read permission only to principals trusted with every namespace they can reach, revoking and reissuing credentials through a mechanism that does not leave prior pagination state usable, treating history page tokens as sensitive and keeping them out of application logs, traces, error reports, and shared storage, and reducing namespace retention so that a referenced history branch becomes unavailable sooner after a workflow closes. A Payload Codec reduces the sensitivity of disclosed payload bodies but does not prevent the unauthorized read or protect history metadata. A long-running open workflow can outlive its namespace's closed-execution retention duration, because that duration is measured from workflow closure.