{"id":"GHSA-9q4h-f4x5-ffq8","summary":"Hatchet: Cross-tenant durable callback payload disclosure in Hatchet V1 Dispatcher","details":"## Summary\n\nThe V1 `DurableTask` stream handler registers worker-supplied durable task external IDs in an in-memory callback routing map before verifying that the authenticated tenant owns the task. If the tenant-scoped ownership check fails, the handler logs the error and continues, but the map entry persists until the stream closes.\n\nDurable callback delivery resolves the destination stream by `task_external_id` only, without checking tenant identity. As a result, a tenant A worker that knows a tenant B durable task external UUID can hold its stream open and receive tenant B's durable callback result payload when the callback is delivered on the same dispatcher process.\n\n## Impact\n\nThis advisory requires an attacker to successfully guess a durable task external UUID belonging to another tenant. Durable task external IDs are generated with `uuid.New()` (UUIDv4) and are not enumerable across tenants, so exploitation requires prior knowledge of a target task UUID through an out-of-band channel. Thus, while the following environments are impacted, there is an extremely low probability it would be exploited. \n\n**Who is impacted.** Any Hatchet deployment that hosts more than one tenant on the same instance:\n- Hatchet Cloud (multi-tenant SaaS) \n- Self-hosted Hatchet with multiple internal teams / business units sharing one instance\n- Any deployment where a single tenant's API token can be obtained by an attacker\n\nSingle-tenant self-hosted deployments are unaffected in practice (the \"victim\" and \"attacker\" tenants would be the same).","aliases":["CVE-2026-84298","GO-2026-6561"],"modified":"2026-10-01T20:56:05.514832277Z","published":"2026-09-22T20:40:43Z","database_specific":{"cwe_ids":["CWE-639","CWE-862"],"severity":"LOW","github_reviewed":true,"github_reviewed_at":"2026-09-22T20:40:43Z","nvd_published_at":"2026-09-21T16:17:24Z"},"references":[{"type":"WEB","url":"https://github.com/hatchet-dev/hatchet/security/advisories/GHSA-9q4h-f4x5-ffq8"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-84298"},{"type":"WEB","url":"https://github.com/hatchet-dev/hatchet/commit/9555bfdd1e97f61d25e614ccaa107c5fb7dc4976"},{"type":"PACKAGE","url":"https://github.com/hatchet-dev/hatchet"}],"affected":[{"package":{"name":"github.com/hatchet-dev/hatchet","ecosystem":"Go","purl":"pkg:golang/github.com/hatchet-dev/hatchet"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"0.95.3"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/09/GHSA-9q4h-f4x5-ffq8/GHSA-9q4h-f4x5-ffq8.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N"}]}