# Tinyauth: User enumeration attack by timing oracle

Advisory record · `GHSA-456h-ww26-f758`

- **Identifiers:** `GHSA-456h-ww26-f758` · `CVE-2026-77582` · `GO-2026-6555`
- **State:** Confirmed
- **Severity:** CVSS 6.9 Medium
- **Critical:** No
- **Weakness (CWE):** [CWE-208](https://cwe.mitre.org/data/definitions/208.html)
- **Tags:** [CWE-208](https://agentprime.io/advisories/tag/cwe-208.md)
- **Published:** 22 Sept 2026
- **Updated:** 1 Oct 2026
- **Reviewed by a person:** No

Published by the GitHub Advisory Database at 22 Sept 2026, 20:37 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

## Affected packages

- `github.com/tinyauthapp/tinyauth` (Go): affected `<1.0.1-0.20260714134959-c22925c2fba9`; fixed in `1.0.1-0.20260714134959-c22925c2fba9`

## Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

> Tinyauth, Go module github.com/tinyauthapp/tinyauth, versions before 1.0.1-0.20260714134959-c22925c2fba9, lets a remote attacker tell whether a local username exists by timing login attempts. Login with a nonexistent user returns much faster than with an existing user, so the difference reveals valid accounts. Upgrade to 1.0.1-0.20260714134959-c22925c2fba9 or later. The source does not list a workaround.

Written 1 Nov 2026.

## Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

## Severity and exploitation

- 6.9 Medium, CVSS 4.0: `CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N`, from CNA (GitHub_M)

- **CISA KEV:** Not listed.
- **EPSS:** 0.0063, the 50th percentile, on 6 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

## Timeline

- 31 Oct 2026, 14:12 UTC: First seen by agentprime
- 31 Oct 2026, 14:12 UTC: [Confirmed by OSV](https://osv.dev/vulnerability/GHSA-456h-ww26-f758)

## Sources

- [GitHub Advisory Database: GHSA-456h-ww26-f758](https://github.com/advisories/GHSA-456h-ww26-f758)
- [OSV: GHSA-456h-ww26-f758](https://osv.dev/vulnerability/GHSA-456h-ww26-f758)
- <https://github.com/tinyauthapp/tinyauth/security/advisories/GHSA-456h-ww26-f758>
- <https://nvd.nist.gov/vuln/detail/CVE-2026-77582>
- <https://github.com/tinyauthapp/tinyauth/pull/1004>
- <https://github.com/tinyauthapp/tinyauth/commit/c22925c2fba981875d0a2b09dd3ee41c0ae4c310>
- <https://github.com/tinyauthapp/tinyauth>
- <https://github.com/tinyauthapp/tinyauth/releases/tag/v5.1.0>

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.

## Check whether this affects you

A Match means an installed version is in the affected range above. Most don’t affect the app; agentprime hasn’t analysed this one yet.

- With the agentprime MCP server (<https://api.agentprime.io/mcp>), ask your agent to check the project: `check_lockfile` sends a lockfile, `check_packages` a list of installed packages, and both return the Matches and the upgrades that clear them. `get_advisory` returns this record. Setup: <https://agentprime.io/mcp.md>
- In a browser: <https://agentprime.io/check/> reads your lockfile in the browser, never uploading it.
- Whether it touches your code, with file and line: the Claude Code plugin, <https://agentprime.io/plugin.md>
- As JSON: <https://api.agentprime.io/v1/advisories/GHSA-456h-ww26-f758>, or `POST https://api.agentprime.io/v1/match` with your packages (<https://agentprime.io/api.md>)

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The web page: <https://agentprime.io/advisories/GHSA-456h-ww26-f758/>. Everything for agents: <https://agentprime.io/llms.txt>.