{"answers":{"affected":"","exploited":"There is no known exploitation of CVE-2026-87858 in the wild and no public exploit code.","fix":"No fix has been published for CVE-2026-87858 yet. Limit exposure of the affected software until one is available.","what":"CVE-2026-87858 is a high-severity missing authorization vulnerability in Temporal Server, published on 21 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim."},"fix_prompt":"Check this codebase for CVE-2026-87858 and fix it if it is affected.\n\nWhat it is: CVE-2026-87858 is a high-severity missing authorization vulnerability in Temporal Server, published on 21 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.\nExploitation: There is no known exploitation of CVE-2026-87858 in the wild and no public exploit code.\n\nAffected product: Temporal Server. No package-level version data is available, so check the vendor advisory linked from the reference page.\n\nTask:\n1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.\n2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.\n3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.\n4. Run the tests and summarise what changed and why.\n5. If nothing in the project is affected, say so and change nothing.\n\nReference: https://insights.sbomify.com/CVE-2026-87858/ (Markdown: https://insights.sbomify.com/CVE-2026-87858/index.md)","id":"CVE-2026-87858","markdown":"https://insights.sbomify.com/CVE-2026-87858/index.md","name":"CVE-2026-87858","record":{"aliases":["GHSA-vrgw-vghm-5p74"],"analysis":{"component_type":"server_software","fix_type":"patch","impacts":["privilege_escalation","data_modify"],"network_reachable":"yes","non_default_config":true,"product_category":"Temporal Server","requires_auth":"low_privilege","summary":"Authenticated users can bypass authorization to perform administrative actions in other namespaces by manipulating callback headers.","user_interaction":"not_required","vuln_class":"missing_authorization"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"Temporal","cpe":[],"cvss":{"score":7.2,"severity":"high","source":"cna","vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N","version":"4.0"},"cwes":[{"id":"CWE-807","name":"Reliance on Untrusted Inputs in a Security Decision"}],"description":"Temporal Server decided whether a Workflow completion callback was internal by reading a caller-supplied HTTP header. An authenticated caller holding only write permission in a single namespace could attach a completion callback whose URL host matched the configured callback address allowlist, whose URL path was any Temporal HTTP API route, and whose header map contained a non-empty header named source. When the History service delivered that callback, the non-empty source header caused it to re-target the request at the local frontend client and rewrite only the scheme and host, preserving the caller's path, query, and request body. Where an internal frontend is deployed with its HTTP API enabled, that client resolves to the internal frontend, which authorizes every request as a system administrator without requiring authentication information. The result is that the server performs an attacker-chosen state-changing HTTP POST against its own administrative API on the caller's behalf, in namespaces where the caller has no permission. The caller never needs network access to the internal frontend, because the History service makes the request. Confirmed effects include terminating Workflows in other namespaces, registering namespaces, modifying another namespace's configuration, and deleting another namespace and its Workflows. The affected routing logic is present in both the HSM and CHASM callback delivery implementations. This description and the CVSS score in this record describe releases 1.30.0 and later, where any non-empty source header is sufficient. Releases 1.25.0 through 1.29.7 are affected by a narrower form of the same defect in which the header must exactly match a configured cluster ID, a UUID that a namespace-scoped caller cannot read through the API. The consequence once that match occurs is the same, but the attack is materially harder and scores lower. To determine whether a deployment is affected, check two settings together: the static Server configuration for a non-zero services.internal-frontend.rpc.httpPort, and the effective per-namespace dynamic configuration value of component.callbacks.allowedAddresses. A deployment is exposed only when an internal frontend is deployed with a non-zero HTTP port, at least one allowlist rule admits a host, and authorization is enabled. The allowlist is empty by default, which denies all external callback URLs, and the stock static topology does not include an internal frontend. Note that a failed attach returns the error 'invalid url: url does not match any configured callback address', which proves only that one tested URL did not match and does not prove the effective allowlist is empty. To look for callbacks already attached, use DescribeWorkflowExecution, which returns callback information for a Workflow's registered completion callbacks. Operators should be aware of a gap when searching for evidence of delivery: the frontend HTTP API server records the request method and URL at debug level only, so at default log levels a delivered request is not written to the internal frontend's logs, and the absence of such log entries is not evidence that the issue was not exploited.","ecosystems":[],"exploits":{"exploitdb":0,"first_seen":null,"github_poc":0,"max_poc_stars":null,"metasploit":0,"nuclei":0,"refs":[],"tier":"none_known"},"has_fix":false,"headline":"Missing authorization in Temporal Server","id":"CVE-2026-87858","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":null,"product":null,"products":[],"type":"missing_authorization","year":"2026"},"n_packages":0,"n_references":6,"next":{"headline":"morgan vulnerable to Log Injection via unescaped double quote in quoted log fields","id":"CVE-2026-87859"},"packages":[],"prev":{"headline":"JTL-Connector for WooCommerce \u003c= 2.4.3 - Unauthenticated Arbitrary File Upload via 'image.push' Method","id":"CVE-2026-87855"},"products":["Temporal Server"],"published":"2026-09-21","related":[],"sources":[{"class":"attribution","licence":"CVE Terms of Use (MITRE)","name":"CVE List","prefix":"CVE"},{"class":"attribution","licence":"CWE Terms of Use","name":"CWE (MITRE)"},{"class":"attribution","licence":"FIRST CVSS licence","name":"CVSS (FIRST)"}],"ssvc":{"automatable":"no","exploitation":"none","technical_impact":"partial"},"state":"PUBLISHED","updated":"2026-09-21","vendors":["Temporal Technologies, Inc."]},"summary":"Authenticated users can bypass authorization to perform administrative actions in other namespaces by manipulating callback headers.","url":"https://insights.sbomify.com/CVE-2026-87858/"}