Authorization Bypass Through User-Controlled Key Affecting go.temporal.io/server/chasm/lib/callback package, versions >=1.30.0 <1.30.8>=1.31.0 <1.31.4>=1.32.0 <1.32.1
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Start learning- Snyk IDSNYK-GOLANG-GOTEMPORALIOSERVERCHASMLIBCALLBACK-20937817
- published14 Oct 2026
- disclosed12 Oct 2026
- creditUnknown
Introduced: 12 Oct 2026
NewCVE-2026-89140 (opens in a new tab)How to fix?
Upgrade go.temporal.io/server/chasm/lib/callback to version 1.30.8, 1.31.4, 1.32.1 or higher.
Overview
Affected versions of this package are vulnerable to Authorization Bypass Through User-Controlled Key via the internal completion callback process. An attacker can alter schedule state across namespaces by attaching a forged callback to a workflow start request, enabling unauthorized changes such as marking actions as completed, bypassing overlap policies, or pausing schedules by forging failures. This is only exploitable if the attacker knows the target namespace identifier, schedule identifier, and the identity and timing of a running action.
Workaround
This vulnerability can be mitigated by preventing the creation of new Scheduler V2 schedules: leave history.enableCHASMSchedulerCreation set to false, and on 1.32.0 leave history.chasmSchedulerCreationRolloutPercent at 0; do not include chasm-scheduler in frontend.allowedExperiments; and leave history.enableCHASMSchedulerMigration set to false.