CVE.org (no NVD analysis yet)· CNA Temporal

CVE-2026-87857: Temporal Server workflow-history pagination token is not bound to the requested namespace and workflow

Noroxi assessment

Priority: Monitor (action score 21/100)

The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
Probability of exploitation in the next 30 days: 0.39% (FIRST EPSS).
Anyone who can reach it over the internet can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
Fixed version: Temporal Technologies, Inc. Temporal Server 1.30.7, 1.31.3.

Low priority for now. Upgrade to Temporal Technologies, Inc. Temporal Server 1.30.7, 1.31.3 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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.

MediumCVSS 5.3 · v4.0—No exploit Fix available

Broken access control (IDOR)

EUVD-2026-120396

Published: Nov 9, 2026
Updated: Nov 9, 2026
EPSS: 0.3% · 34th percentile
CWE: CWE-639

Report tools

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Action score

Monitor

Low priority for now.

CVSS: 21 / 40 · 5.3 / 10
CISA KEV: 0 / 30 · Not listed
EPSS: 0 / 30 · 0.3%

CNA vs NVD score

NVD: —
CNA · Temporal: 5.3; NVD has not scored this yet; the score shown is the CNA’s.

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

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

Not in KEV: no record of exploitation in the wild
No public exploit code on record
A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Is your version affected? Check it

Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

—

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Temporal). Independent of NVD's CPE analysis and usually ahead of it.

Temporal Technologies, Inc. Temporal Server
- 0.0.0 and later · before 1.0.0unknown · semver
- 1.0.0 and later · up to and including 1.29.7affected · semver
- 1.30.0 and later · before 1.30.7affected · semver
- 1.31.0 and later · before 1.31.3affected · semver

Same product

Other highest-scoring records for the same primary product.

CVE-2026-120091Temporal Server Kubernetes compute provider builds a client from caller-supplied configuration and runs a caller-chosen command on the Worker Service host
34Monitor
CVE-2026-89139Temporal Server worker deployment compute provider executes a caller-supplied command on the Worker Service host
34Monitor
CVE-2026-104355Temporal Server applies inbound namespace replication from a connected peer cluster to local namespaces
28Monitor

Published before and after this one in the same product

← EarlierCVE-2026-16652Sep 21, 2026 · Temporal Server Schedule exclusion search can cause excessive CPU consumption
28Monitor
← EarlierCVE-2026-87858Sep 21, 2026 · Temporal Server completion callback source header can direct attacker-chosen requests to the internal frontend with administrator authorization
28Monitor
← EarlierCVE-2026-89140Oct 12, 2026 · Temporal Server internal completion callbacks are not bound to their namespace, allowing cross-namespace changes to Scheduler V2 schedule state
24Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / package	Fixed version	Source
Temporal Technologies, Inc. Temporal Server	1.30.7	Vendor (CNA)
Temporal Technologies, Inc. Temporal Server	1.31.3	Vendor (CNA)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

PublishedNov 9, 2026
Fix recordedNov 9, 2026same day
TodayNov 11, 2026+1 d

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

Reported internallyTemporal Technologies, Inc.finder

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

CVE-2026-8914028 days apartTemporal Server internal completion callbacks are not bound to their namespace, allowing cross-namespace changes to Scheduler V2 schedule state
24Monitor

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

Anyone who can reach it over the internet can trigger it.
A low-privileged account is enough.
No user action is required.
No special conditions are required; it is repeatable.

If successful

Confidentiality
Integrity
Availability

Attack vector: Network
Attack complexity: Low
Privileges required: Low
User interaction: None
Scope: X

Weakness class (CWE)

CWE-639 · Authorization Bypass Through User-Controlled Key

CVSS vector

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

nvd-secondary

Root cause

The endpoint fetches the record by the ID sent in the request, but never checks whether the record belongs to the requesting user.

The bug in code

The whole CWE-639 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

1const invoice = await Invoice.findById(req.params.id);
2res.json(invoice);

Fixed

1const invoice = await Invoice.findOne({
2  id: req.params.id,
3  ownerId: req.user.id,
4});
5if (!invoice) return res.sendStatus(404);
6res.json(invoice);

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

Exploit maturity— → noneNov 9, 2026, 9:07 PM UTC
Fix✗ → ✓Nov 9, 2026, 9:07 PM UTC

For records you follow, these changes also arrive as notifications. →

References

github.com/temporalio/temporal/blob/v1.0.0/service/frontend/workflowHandler.go#L602-L740

Show all references (11 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

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