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

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

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

EPSS

• CVE-2026-77560: 0.61% estimated exploitation activity in the next 30 days; percentile 49.38 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

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 GitHub Advisory Details (form fields — paste-ready) Affected products | Field | Value | |-------|-------| | Ecosystem | Other (self-hosted) / Go | | Package name | github.com/steveiliop56/tinyauth (forward-auth middleware) | | Affected versions | < 5.1.2 | | Patched versions | 5.1.2 | Advisory details | Field | Value | |-------|-------| | Title | tinyauth forward-auth authorization bypass: per-app ACL host matching is case-sensitive while hostnames are case-insensitive, so a mixed-case host defeats users/groups/ip allowlists and fails open | - Status: Runtime-confirmed (local lab, 127.0.0.1 only) - Target: steveiliop56/tinyauth v5.0.7 (commit 479f1657812b7bf01438607464dedaa148155301); root cause also present on main HEAD - Component: internal/service/accesscontrolsservice.go (lookupStaticACLs /…

Published by the source

22 Sep 2026, 20:37 UTC

Last modified by the source

1 Oct 2026, 20:45 UTC

Source last checked

26 Oct 2026, 15:29 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-328g-jx67-v94g

2. Revision 2 · amended · 24 Oct 2026

   Amended from osv record GO-2026-6552

3. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-328g-jx67-v94g

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# Patch Next advisory brief: CVE-2026-77560

Advisory: 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
IDs: CVE-2026-77560, GHSA-328g-jx67-v94g
Record: https://patchnext.com/advisories/cve-2026-77560 (revision 3, source checked 26 Oct 2026, 15:29 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.1)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/tinyauthapp/tinyauth 1.0.1-0.20260720133915-80bc87188ec3. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/tinyauthapp/tinyauth: affected < 1.0.1-0.20260720133915-80bc87188ec3; fixed in 1.0.1-0.20260720133915-80bc87188ec3

## Suggested inspection (read-only)
- Go github.com/tinyauthapp/tinyauth: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/tinyauthapp/tinyauth.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-328g-jx67-v94g (OSV record GHSA-328g-jx67-v94g lists affected ranges: Go github.com/tinyauthapp/tinyauth >=0 <1.0.1-0.20260720133915-80bc87188ec3 (fixed))
- Verified: https://osv.dev/vulnerability/GO-2026-6552 (OSV record GO-2026-6552 lists affected ranges: Go github.com/tinyauthapp/tinyauth >=0 <1.0.1-0.20260720133915-80bc87188ec3 (fixed))
- Verified: https://github.com/advisories/GHSA-328g-jx67-v94g (GitHub-reviewed advisory GHSA-328g-jx67-v94g lists affected ranges: Go github.com/tinyauthapp/tinyauth >=0 <1.0.1-0.20260720133915-80bc87188ec3)

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