# CVE-2026-80199: Kimai TokenAuthenticator username enumeration via timing oracle

Source: https://junglewise.ai/threats/cve-2026-80199-kimai-tokenauthenticator-username-enumeration-via-timing-oracle  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-08-26. Updated: 2026-09-25  
License: CC BY 4.0 with a link back

CVE-2026-80199 · Severity: low · CVSS 3.7 · Published 2026-08-26

Kimai is a time-tracking and billing application used by organizations to manage employee work hours. The authentication system leaks information about whether a username exists through measurable differences in response time, allowing attackers to discover valid user accounts without credentials. This weakens security by enabling attackers to build a list of real users to target with password attacks.

Technologies: [Kimai](https://junglewise.ai/threats/technologies/kimai), [kimai/kimai (Packagist)](https://junglewise.ai/threats/technologies/kimai-kimai). Vendors: [Kimai](https://junglewise.ai/threats/vendors/kimai), [Packagist](https://junglewise.ai/threats/vendors/packagist).

## Quick answers

**Is CVE-2026-80199 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-80199 being exploited in the wild.

**How severe is CVE-2026-80199?** Low severity, with a CVSS score of 3.7, published 26 August 2026.

**Which products and versions are affected?** Kimai before 2.54.0; kimai/kimai (Packagist) ECOSYSTEM:introduced=0,fixed=2.54.0.

**Is there a fix for CVE-2026-80199?** Yes. kimai/kimai (Packagist): upgrade to 2.54.0 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-80199 attacked?** It is attacked over the network, in a web application.

**Am I affected by CVE-2026-80199?** Check whether you run Kimai or kimai/kimai (Packagist) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- kimai/kimai (Packagist): upgrade to 2.54.0 or later

  ```sh
  composer require kimai/kimai:^2.54.0
  ```


## Technical details

A timing oracle vulnerability exists in TokenAuthenticator.php where the password hasher (argon2id) is only invoked when a user is found via loadUserByIdentifier(). When a non-existent username is queried, the response returns approximately 25 ms faster than for a valid username, despite returning identical HTTP 403 responses with the same error message. The legacy X-AUTH-USER and X-AUTH-TOKEN headers accept unauthenticated requests to the /api/* endpoints with no login throttling, allowing unbounded probing. An attacker can enumerate valid usernames by measuring response times from the /api/users/me endpoint. The vulnerability is fixed in version 2.54.0 by running the password hasher against a fixed dummy hash even when the user is not found, ensuring constant-time responses regardless of user existence.

## Affected products

- Kimai Kimai before 2.54.0

## Identifiers

- CVE-2026-80199
- GHSA-jrc6-fmhw-fpq2

## Timeline

- 2026-04-16: disclosed
- 2026-08-25: advisory
- 2026-04-16: patched: patched in version 2.54.0

## References

- [https://github.com/kimai/kimai/security/advisories/GHSA-jrc6-fmhw-fpq2](https://github.com/kimai/kimai/security/advisories/GHSA-jrc6-fmhw-fpq2)
- [https://www.vulncheck.com/advisories/kimai-before-2.54.0-username-enumeration-via-timing-oracle](https://www.vulncheck.com/advisories/kimai-before-2.54.0-username-enumeration-via-timing-oracle)

## Related threats

- [Kimai missing authorization check in ExportController export templates](https://junglewise.ai/threats/cve-2026-52828-kimai-missing-authorization-check-in-exportcontroller-export)
- [Kimai 2FA bypass in REST API via session cookie replay](https://junglewise.ai/threats/cve-2026-52827-kimai-2fa-bypass-in-rest-api-via-session-cookie-replay)
- [Kimai improper authorization in rate edit endpoints](https://junglewise.ai/threats/cve-2026-52826-kimai-improper-authorization-in-rate-edit-endpoints)
- [Kimai improper authorization in Team assignment APIs](https://junglewise.ai/threats/cve-2026-52825-kimai-improper-authorization-in-team-assignment-apis)
- [Kimai insecure default APP_SECRET in Docker image](https://junglewise.ai/threats/cve-2026-52824-kimai-insecure-default-app-secret-in-docker-image)