Hatchet - Unauthenticated OAuth state CSRF / login-CSRF via empty-state collision in ValidateOAuthState

### Summary Hatchet version v0.86.26 and below is vulnerable to OAuth state CSRF (login CSRF / account fixation). The vulnerable code clears the session `oauth_state_<integration>` value to the empty string `""` after a successful OAuth callback rather than removing the key, and the subsequent state-equality check then accepts an empty `?state=` parameter on any later callback request — allowing an unauthenticated attacker to bind an already-authenticated victim's session cookie to an attacker-controlled OAuth identity (account takeover via login-CSRF). ### Impact Affected configurations: any deployment that has enabled at least one of `auth.google.enabled`, `auth.github.enabled`, or the Slack integration, and where the victim has completed at least one OAuth flow on that integration in the current session. Bug present on `main` HEAD and in every tagged release up to and including v0.86.26 (commit `243f41d9e1161e70d47dfc0a6509f1c4ddfc9c23`).

Source published

21 Sep 2026 15:47:01 UTC

Source modified

28 Sep 2026 17:11:11 UTC

Observed here

24 Oct 2026 13:19:41 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V3 · CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:H/A:N

Publisher rating · HIGH