Vulnerabilities in pkg:golang/go.temporal.io/server

PACKAGE
Advisory Identifier: GHSA-xpg8-3hhp-p7w8
Advisory Summary

CVE-2026-5199 is a LOW attacker-controlled namespace could signal, delete, vulnerability (CWE-639: Authorization Bypass Through User-Controlled Key) affecting Temporal Server libraries in the Go ecosystem. The issue involves attacker-controlled namespace could signal, delete, and reset workflows or activities in a victim namespace on the same cluster. Remediation is available by upgrading affected packages to version 1.30.3, 1.29.5.

6 Known Advisory Record(s)
Package Vulnerability Intelligence

pkg:golang/go.temporal.io/server

6 Known Advisory Record(s)

Vulnerability advisories affecting package pkg:golang/go.temporal.io/server. Select an advisory below to view technical details or fixes.

Advisory ID CVE / NVD Severity Summary
GHSA-xpg8-3hhp-p7w8 CVE-2026-5199 LOW Temporal Server: attacker-controlled namespace could signal, delete, and reset workflows or activities in a victim namespace on the same cluster
GHSA-q98v-9f9w-f49q CVE-2026-5724 MODERATE Temporal does not enforce authentication and authorization for the streaming AdminService/StreamWorkflowReplicationMessages endpoint
GHSA-hmhp-gh8m-c8xp CVE-2025-14987 MODERATE Temporal has an Incorrect Authorization vulnerability
GHSA-p2gr-hm8g-q772 CVE-2025-14986 LOW Temporal has a namespace policy bypass allowing requests to be authorized for incorrect contexts
GHSA-p768-c3pr-6459 CVE-2025-8396 MODERATE Temporal OSS Server Vulnerable to Allocation of Resources Without Limits or Throttling
GHSA-gm2g-2xr9-pxxj CVE-2023-3485 LOW Temporal Server vulnerable to Incorrect Authorization and Insecure Default Initialization of Resource

CVE-2026-5199 at a Glance

CVE Identifier CVE-2026-5199
GHSA Identifier GHSA-xpg8-3hhp-p7w8
Severity LOW
CVSS v3.1 Base Score N/A
CWE Classification CWE-639: Authorization Bypass Through User-Controlled Key
Affected Product Temporal Server
Package Ecosystem Go
Published Date
Last Updated

How to Fix CVE-2026-5199

To remediate this vulnerability, upgrade all affected Temporal Server dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

go.temporal.io/server fixed: 1.30.3
Upgrade go.temporal.io/server to 1.30.3
go.temporal.io/server fixed: 1.29.5
Upgrade go.temporal.io/server to 1.29.5
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release:

inspect dependencies for go.temporal.io/server

How to Check if You Are Affected

To determine whether your application is affected by CVE-2026-5199, inspect your project dependencies for Temporal Server:

inspect dependencies for go.temporal.io/server

Analyze the terminal output to locate any version of Temporal Server in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 1.30.3), your application is affected.

Note: Verify declared build manifests and deployed runtime container environments.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-639: Authorization Bypass Through User-Controlled Key, where the system's authorization functionality does not prevent one user from gaining access to another user's data or record by modifying the key value identifying the data. In Temporal Server, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

A writer role user in an attacker-controlled namespace could signal, delete, and reset workflows or activities in a victim namespace on the same cluster. Exploitation requires the attacker to know or guess specific victim workflow ID(s) and, for signal operations, signal names. This was due to a bug introduced in Temporal Server v1.29.0 which inadvertently allowed an attacker to control the namespace name value instead of using the server's own trusted name value within the batch activity code. The batch activity validated the namespace ID but did not cross-check the namespace name against the worker's bound namespace, allowing the per-namespace worker's privileged credentials to operate on an arbitrary namespace. Exploitation requires a server configuration where internal components have cross-namespace authorization, such as deployment of the internal-frontend service or equivalent TLS-based authorization for internal identities. This vulnerability also impacted Temporal Cloud when the attacker and victim namespaces were on the same cell, with the same preconditions as self-hosted clusters.

CVE-2026-5199 Affected Temporal Server Versions

2 component(s)
Fixed Versions:
1.30.31.29.5
Product / Package Ecosystem Affected Versions Fixed Version
go.temporal.io/server
Go
≥ 1.30.0-143.0
< 1.30.3
1.30.3
go.temporal.io/server
Go
< 1.29.5
1.29.5

References

Frequently Asked Questions

What is CVE-2026-5199?
CVE-2026-5199 is a security vulnerability in Temporal Server involving attacker-controlled namespace could signal, delete, and reset workflows or activities in a victim namespace on the same cluster under CWE-639: Authorization Bypass Through User-Controlled Key.
Which Temporal Server versions are affected?
Affected versions include releases prior to 1.30.3, 1.29.5 across affected packages: go.temporal.io/server.
What version fixes CVE-2026-5199?
Upgrading to 1.30.3, 1.29.5 (or the latest patched release for your respective branch) resolves the vulnerability.
Is go.temporal.io/server affected?
Yes, go.temporal.io/server is affected in releases prior to 1.30.3, 1.29.5. Upgrade your dependency to 1.30.3, 1.29.5 or later.
What CWE is associated with CVE-2026-5199?
CVE-2026-5199 is classified under CWE-639: Authorization Bypass Through User-Controlled Key (The system's authorization functionality does not prevent one user from gaining access to another user's data or record by modifying the key value identifying the data.).
How can I check Go dependencies for CVE-2026-5199?
Run the dependency tree command: 'inspect dependencies for go.temporal.io/server'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-xpg8-3hhp-p7w8",
  "modified" : "2026-07-21T14:59:09Z",
  "published" : "2026-04-01T18:36:38Z",
  "aliases" : [ "CVE-2026-5199" ],
  "summary" : "Temporal Server: attacker-controlled namespace could signal, delete, and reset workflows or activities in a victim namespace on the same cluster",
  "details" : "A writer role user in an attacker-controlled namespace could signal, delete, and reset workflows or activities in a victim namespace on the same cluster. Exploitation requires the attacker to know or guess specific victim workflow ID(s) and, for signal operations, signal names. This was due to a bug introduced in Temporal Server v1.29.0 which inadvertently allowed an attacker to control the namespace name value instead of using the server's own trusted name value within the batch activity code. The batch activity validated the namespace ID but did not cross-check the namespace name against the worker's bound namespace, allowing the per-namespace worker's privileged credentials to operate on an arbitrary namespace. Exploitation requires a server configuration where internal components have cross-namespace authorization, such as deployment of the internal-frontend service or equivalent TLS-based authorization for internal identities.\n\nThis vulnerability also impacted Temporal Cloud when the attacker and victim namespaces were on the same cell, with the same preconditions as self-hosted clusters.",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:N/VI:L/VA:L/SC:N/SI:L/SA:L"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Go",
      "name" : "go.temporal.io/server"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "1.30.0-143.0"
      }, {
        "fixed" : "1.30.3"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "Go",
      "name" : "go.temporal.io/server"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "1.29.5"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-5199"
  }, {
    "type" : "ADVISORY",
    "url" : "https://github.com/advisories/GHSA-xpg8-3hhp-p7w8"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/temporalio/temporal"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/temporalio/temporal/releases/tag/v1.29.5"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/temporalio/temporal/releases/tag/v1.30.3"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-639" ],
    "severity" : "LOW",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-04-03T23:25:37Z",
    "nvd_published_at" : "2026-04-01T18:16:31Z"
  }
}