# CVE-2026-91972: Vikunja API v2 missing rate limiting on authentication endpoints

Source: https://junglewise.ai/threats/cve-2026-91972-vikunja-api-v2-missing-rate-limiting-on-authentication-endpoints  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-15. Updated: 2026-09-26  
License: CC BY 4.0 with a link back

CVE-2026-91972 · Severity: high · CVSS 7.5 · Published 2026-09-15

Vikunja is a task and project management application that provides REST APIs for authentication and account management. Versions before 2.6.0 fail to apply rate limiting to public authentication endpoints in the v2 API (login, registration, password reset), while the v1 API correctly enforces limits. This allows attackers to perform unlimited credential-guessing attacks, enumerate valid user accounts, and flood password-reset functions without throttling, potentially compromising user accounts.

Technologies: [code.vikunja.io/api (Go)](https://junglewise.ai/threats/technologies/code-vikunja-io-api), [Vikunja](https://junglewise.ai/threats/technologies/vikunja). Vendors: [Go](https://junglewise.ai/threats/vendors/go), [Vikunja](https://junglewise.ai/threats/vendors/vikunja).

## Quick answers

**Is CVE-2026-91972 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-91972 being exploited in the wild.

**How severe is CVE-2026-91972?** High severity, with a CVSS score of 7.5, published 15 September 2026.

**Which products and versions are affected?** code.vikunja.io/api (Go) <= 2.5.0, SEMVER:introduced=0, SEMVER:introduced=0,fixed=2.6.0; Vikunja before 2.6.0.

**Is there a fix for CVE-2026-91972?** Yes. code.vikunja.io/api (Go): upgrade to 2.6.0 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-91972 attacked?** It is attacked over the network.

**Am I affected by CVE-2026-91972?** Check whether you run code.vikunja.io/api (Go) or Vikunja 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

- code.vikunja.io/api (Go): upgrade to 2.6.0 or later

  ```sh
  go get code.vikunja.io/api@v2.6.0
  ```


## Technical details

The vulnerability is a missing rate-limit enforcement (CWE-307) in the API routing layer. The registerAPIRoutesV2() function in pkg/routes/routes.go fails to apply the unauthRateLimit() middleware (a default per-IP floor of 10 requests per 60 seconds) to public authentication endpoints, instead relying on setupRateLimit() which is configuration-gated and disabled by default. This contrasts with the v1 API implementation, which unconditionally applies unauthRateLimit() to all pre-auth routes. The attack is network-reachable, requires no authentication or user interaction, and enables unbounded brute-force attacks against login, registration, and password-reset endpoints. The fix (version 2.6.0+) applies the unconditional rate-limit floor to v2 public route groups.

## Affected products

- Vikunja Vikunja before 2.6.0

## Identifiers

- CVE-2026-91972
- GHSA-6rvj-qwjf-3m4q
- GO-2026-6721

## Timeline

- 2026-08-31: disclosed
- 2026-09-15: patched

## References

- [https://github.com/go-vikunja/vikunja/security/advisories/GHSA-6rvj-qwjf-3m4q](https://github.com/go-vikunja/vikunja/security/advisories/GHSA-6rvj-qwjf-3m4q)
- [https://www.vulncheck.com/advisories/vikunja-before-2.6.0-authentication-bypass-via-unthrottled-api](https://www.vulncheck.com/advisories/vikunja-before-2.6.0-authentication-bypass-via-unthrottled-api)

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- [Vikunja missing authentication in TOTP enrollment](https://junglewise.ai/threats/cve-2026-123530-vikunja-before-2-7-1-contains-a-missing-authentication)
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