Tinyauth: forward-auth per-app ACL is matched case-sensitively against the (case-insensitive) hostname, letting an authenticated user reach apps they are not on the allowlist for

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-77560
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-21 17:18:52 UTC
Updated2026-09-24 21:25:27 UTC
DescriptionTinyauth is an authentication and authorization server. Prior to 5.1.2, Tinyauth compares forwarded hostnames case-sensitively while reverse proxies route equivalent hostnames case-insensitively, allowing an authenticated low-privilege user to bypass per-app access controls with a differently cased hostname. The lookup in internal/service/access_controls_service.go through lookupStaticACLs and GetAccessControls, and the Docker-label fallback in internal/service/docker_service.go through GetLabels, can miss the configured app and return an empty access-control object. internal/controller/proxy_controller.go proxyHandler then treats the empty user, group, OAuth, LDAP, and IP restrictions as permissive and returns an authenticated result for an app that should exclude the user. Unauthenticated users remain subject to login, and global login-time allowlists are not bypassed. This issue is fixed in version 5.1.2.

Risk And Classification

Primary CVSS: v3.1 8.1 HIGH from [email protected]

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

EPSS: 0.006120000 probability, percentile 0.470950000 (date 2026-09-25)

Problem Types: CWE-178 | CWE-636 | CWE-863 | CWE-178 CWE-178: Improper Handling of Case Sensitivity | CWE-636 CWE-636: Not Failing Securely ('Failing Open') | CWE-863 CWE-863: Incorrect Authorization

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary8.1HIGHCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
3.1CNADECLARED8.1HIGHCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
None

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Tinyauthapp Tinyauth affected < 5.1.2 Not specified

References

ReferenceSourceLinkTags
github.com/tinyauthapp/tinyauth/pull/1000 [email protected] github.com
github.com/tinyauthapp/tinyauth/security/advisories/GHSA-328g-jx67-v94g [email protected] github.com
github.com/tinyauthapp/tinyauth/commit/e75605b2c534ec83525a33603e16d76ba... [email protected] github.com
github.com/tinyauthapp/tinyauth/pull/1028 [email protected] github.com
github.com/tinyauthapp/tinyauth/commit/80bc87188ec3aabc5104c249eaa7b9979... [email protected] github.com
github.com/tinyauthapp/tinyauth/releases/tag/v5.1.2 [email protected] github.com
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