---
id: "CVE-2026-91972"
kind: "vulnerability"
aliases: ["CVE-2026-91972", "GHSA-6rvj-qwjf-3m4q", "GO-2026-6721"]
title: "Vikunja: Every /api/v2 pre-auth endpoint is unthrottled on a stock install while its /api/v1 twin is rate limited in code.vikunja.io/api"
severity: "high"
cvss: 8.7
epss: 0.00633
exploited: false
status: "open"
category: "package"
products: [{"name": "code.vikunja.io/api", "fixed": [], "affected": "all versions", "ecosystem": "go"}, {"name": "code.vikunja.io/api", "fixed": ["2.6.0"], "affected": "<= 2.5.0", "ecosystem": "go"}]
ecosystems: ["go"]
tags: ["go", "package", "rate-limiting", "self-hosted", "vikunja"]
not_affected_if: ["default-config", "fixed-2.6.0", "managed-hosting"]
published_at: "2026-09-15T16:17:54+00:00"
first_seen_at: "2026-10-23T19:13:08+00:00"
updated_at: "2026-10-23T21:44:34+00:00"
sources: [{"source": "govuln", "url": "https://pkg.go.dev/vuln/GO-2026-6721", "first_seen_at": "2026-10-23T19:13:08+00:00"}, {"source": "epss", "url": "https://api.first.org/data/v1/epss?cve=CVE-2026-91972", "first_seen_at": "2026-10-23T19:13:43+00:00"}, {"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-91972", "first_seen_at": "2026-10-23T19:35:23+00:00"}, {"source": "analyst", "url": null, "first_seen_at": "2026-10-23T21:44:34+00:00"}]
---

# Vikunja: Every /api/v2 pre-auth endpoint is unthrottled on a stock install while its /api/v1 twin is rate limited in code.vikunja.io/api

Vikunja <= 2.5.0 does not apply the unconditional pre-auth per-IP rate limit (unauthRateLimit, default 10/60s) to /api/v2 public routes (login, register, password-reset token, oauth token). v1 twins are throttled, but v2 relies on the global limiter, which is off by default. A stock install allows unlimited password guessing, account enumeration and reset flooding. Fixed in 2.6.0.

_Summary, check and fix written by a model from the sources; labelled as such._

## Affected

- go:code.vikunja.io/api affected all versions fixed ?
- go:code.vikunja.io/api affected <= 2.5.0 fixed 2.6.0

## How to check

Check the version: GET /api/v1/info, or run vikunja version. Anything <= 2.5.0 is affected. Test: send about 25 POST requests to /api/v2/login. If you never get a 429, the endpoint is unthrottled; v1 returns 429 from about the 5th attempt. govulncheck will not flag this because the Go DB entry uses unmapped custom versions.

## Fix

Upgrade Vikunja to 2.6.0 or later. Until then, rate limit /api/v2/login, /api/v2/register, /api/v2/user/password/token and the oauth token route at the reverse proxy, or block /api/v2 pre-auth paths if unused.

## Timeline

- 2026-10-23T19:13:08+00:00 govuln https://pkg.go.dev/vuln/GO-2026-6721
- 2026-10-23T19:13:43+00:00 epss https://api.first.org/data/v1/epss?cve=CVE-2026-91972
- 2026-10-23T19:35:23+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-91972
- 2026-10-23T21:44:34+00:00 analyst — Read GHSA-6rvj-qwjf-3m4q (vendor, Moderate, CWE-307) and GO-2026-6721: affected <= 2.5.0, fixed 2.6.0. Go DB shows 'no known fixed' only because custom versions are unmapped; govulncheck ignores it. No exploitation evidence; PoC is in the advisory. Did not search social; low-profile. Advisory rates Moderate, signal says high; severity unchanged.

## Documents

- [advisory] GHSA-6rvj-qwjf-3m4q Vikunja v2 pre-auth endpoints unthrottled https://github.com/go-vikunja/vikunja/security/advisories/GHSA-6rvj-qwjf-3m4q
- [describes] GO-2026-6721 https://pkg.go.dev/vuln/GO-2026-6721

## From the sources

Vikunja: Every /api/v2 pre-auth endpoint is unthrottled on a stock install while its /api/v1 twin is rate limited in code.vikunja.io/api.

NOTE: The source advisory for this report contains additional versions that could not be automatically mapped to standard Go module versions.

(If this is causing false-positive reports from vulnerability scanners, please suggest an edit to the report.)

The additional affected modules and versions are: code.vikunja.io/api before v2.6.0.

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_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_