{"cve":"CVE-2026-33544","nvd":{"published":"2026-04-02T15:16:39.553","modified":"2026-10-26T22:10:00.163","status":"Analyzed","description":"Tinyauth is an authentication and authorization server. Prior to version 5.0.5, all three OAuth service implementations (GenericOAuthService, GithubOAuthService, GoogleOAuthService) store PKCE verifiers and access tokens as mutable struct fields on singleton instances shared across all concurrent requests. When two users initiate OAuth login for the same provider concurrently, a race condition between VerifyCode() and Userinfo() causes one user to receive a session with the other user's identity. This issue has been patched in version 5.0.5.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:N","score":7.7},"cwes":["CWE-362"],"references":["https://github.com/steveiliop56/tinyauth/commit/f26c2171610d5c2dfbba2edb6ccd39490e349803","https://github.com/steveiliop56/tinyauth/releases/tag/v5.0.5","https://github.com/steveiliop56/tinyauth/security/advisories/GHSA-9q5m-jfc4-wc92"],"products":["tinyauth:tinyauth"],"source":"nvd","synced_at":"2026-10-26T22:26:44.656832877+00:00"},"epss":{"cve":"CVE-2026-33544","score":0.00338,"percentile":0.26978,"date":"2026-10-26"},"kev":null,"osv":[{"id":"GHSA-9q5m-jfc4-wc92","url":"https://osv.dev/vulnerability/GHSA-9q5m-jfc4-wc92","summary":"Tinyauth has OAuth account confusion via shared mutable state on singleton service instances","modified":"2026-06-25T19:56:22.982473324Z","packages":[{"ecosystem":"Go","name":"github.com/steveiliop56/tinyauth","purl":"pkg:golang/github.com/steveiliop56/tinyauth","ranges":["<1.0.1-0.20260401140714-fc1d4f2082a5"],"fixed":["1.0.1-0.20260401140714-fc1d4f2082a5"]}]},{"id":"GO-2026-5296","url":"https://osv.dev/vulnerability/GO-2026-5296","summary":"Tinyauth has OAuth account confusion via shared mutable state on singleton service instances in github.com/steveiliop56/tinyauth","modified":"2026-06-25T19:45:27.265267097Z","packages":[{"ecosystem":"Go","name":"github.com/steveiliop56/tinyauth","purl":"pkg:golang/github.com/steveiliop56/tinyauth","ranges":["<1.0.1-0.20260401140714-fc1d4f2082a5"],"fixed":["1.0.1-0.20260401140714-fc1d4f2082a5"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}