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CVE-2026-89140

Vulnerability in Temporal Server (CVE-2026-89140)

Summary

Vulnerability in Temporal Server (CVE-2026-89140). Risk of unauthorized operations or information disclosure.

Original description

The description as published by the source.

Temporal Server does not bind internal completion callbacks to the namespace that attached them, which allows an authenticated caller with write permission in one namespace to alter Scheduler V2 schedule state in another namespace. The callback address temporal://internal is reserved for callbacks that Scheduler V2 attaches to the Workflows it starts. In affected releases, any authenticated caller could attach a callback with that address to a Workflow start request, the address was exempt from the component.callbacks.allowedAddresses allowlist, and the History service delivered the callback to the component its token named, in whatever namespace that was, without authorizing the original caller there. When the forged completion matches an action a target schedule is running, the schedule records the action as completed while its Workflow still runs, which can defeat an overlap policy such as SKIP, and passes caller-controlled data to the next scheduled Workflow as its last completion result. A forged failure may also pause a schedule configured to pause on failure. A forgery requires the target namespace identifier, the schedule identifier, and the identity and timing of a running action. No disclosure of Workflow payloads or history was identified. Only namespaces that hold Scheduler V2 schedules can be targeted; Scheduler V2 is off by default, and existing Scheduler V2 schedules remain targets after the settings that create them are turned off.

Source: NIST National Vulnerability Database NVD GitHub Advisory

Auto-generated summary

Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.

A vulnerability tracked as CVE-2026-89140 has been found in Temporal Server.
Risk of unauthorized operations or information disclosure.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "Temporal Server CVE-2026-89140" on the vendor's site.

CVE-2026-89140 (Temporal Server) — CWE-639
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.

❓ What is the problem

A vulnerability (CWE-639) exists in Temporal Server.

📍 Affected scope

Check the vendor advisory for the affected versions of Temporal Server.

🔥 Severity

Severity: ?. Risk of unauthorized operations or information disclosure.

🔧 How to fix

Update to the patched release per vendor advisory.

🛡️ Workaround

Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.

🔍 Detection

Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Audit SBOM/dependencies to find affected services.

Response actions

Concrete steps and command examples for SOC/SRE teams to execute in order

  1. 1
    Identify exposure identify 
    Audit SBOM/dependencies for affected components.

    資産台帳・SBOM・依存マニフェストで Temporal Server を使っているサービスとバージョンを洗い出す。

  2. 2
    Post-deployment verification verify 
    Confirm patched version is live in production

    パッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。

References

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