{"schema":"threatline.record/2","record":{"id":"CVE-2026-91972","aliases":["GHSA-6rvj-qwjf-3m4q","GO-2026-6721"],"summary":"Vikunja: Every /api/v2 pre-auth endpoint is unthrottled on a stock install while its /api/v1 twin is rate limited","details":"### Summary\n`registerAPIRoutesV2` never applies the unconditional pre-auth rate-limit floor (`unauthRateLimit()`) to the v2 public routes — it passes that limiter only to `/api/v2/ws` — and otherwise relies on `setupRateLimit`, which registers nothing when `ratelimit.enabled` is false (the default). So on a stock install every v2 pre-auth endpoint (login, register, password-reset token, oauth token) is unthrottled, while its v1 twin is throttled.\n\n### Details\n`unauthRateLimit()` -> `perMinuteIPRateLimit(\"noauth\", RateLimitNoAuthRoutesLimit)` (`pkg/routes/rate_limit.go`, ~lines 100-118) is an unconditional per-IP floor (default 10/60s) that deliberately ignores `RateLimitEnabled`, which is why v1's pre-auth routes are throttled even with the global limiter off. v1 applies it: `ur := a.Group(\"\"); ur.Use(unauthRateLimit())` (`pkg/routes/routes.go` ~line 459). `registerAPIRoutesV2` (~lines 405-431) passes the `unauthRateLimit()` instance only to `/api/v2/ws`; its auth routes get only `setupRateLimit(a, ...)`, which is config-gated and registers nothing by default.\n\n### PoC (verified at runtime against v2.5.0)\n```\nPOST /api/v1/login              x25 -> 429 from attempt 5\nPOST /api/v2/login              x25 -> 403 x25, 429 x0\nPOST /api/v1/user/password/token     -> 429 (throttled)\nPOST /api/v2/user/password/token x20 -> 404 x20, 429 x0\n```\nRequest bodies are byte-identical across versions (shared `user.Login` / `user.PasswordTokenRequest`). Both v2 endpoints reach their handlers (403/404, not route-404), so the comparison is valid.\n\n### Impact\nThe pre-auth rate-limit floor — the instance's only default anti-brute-force / anti-abuse control — is absent on all v2 public endpoints. Enables unbounded credential guessing, account-enumeration probing, and password-reset flooding on a default install. Reported as an authentication-control bypass, not a DoS.\n\n### Fix\nApply `unauthRateLimit()` to the v2 public route group, matching v1.","categories":["Libraries & packages"],"product":"code.vikunja.io/api","vendor":"go-vikunja","ecosystem":"go","affected_ranges":[{"source":"GitHub Advisory Database","source_url":"https://github.com/advisories/GHSA-6rvj-qwjf-3m4q","source_modified_at":"2026-10-09T20:51:07Z","fetched_at":"2026-10-23T18:42:43.628194Z","package":{"ecosystem":"go","name":"code.vikunja.io/api"},"range":"<= 2.5.0"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-91972","source_modified_at":"2026-09-17T15:12:40.377Z","fetched_at":"2026-10-23T18:45:31.882637Z","product":"vikunja","vendor":"go-vikunja","versions":[{"version":"0","status":"affected","versionType":"semver","lessThan":"2.6.0"},{"version":"2.6.0","status":"unaffected","versionType":"semver"}],"defaultStatus":"unaffected"},{"source":"OSV","source_url":"https://osv.dev/vulnerability/GHSA-6rvj-qwjf-3m4q","source_modified_at":"2026-10-19T21:41:17.124911538Z","fetched_at":"2026-10-23T18:42:43.628194Z","package":{"ecosystem":"Go","name":"code.vikunja.io/api","purl":"pkg:golang/code.vikunja.io/api"},"ranges":[{"events":[{"introduced":"0"},{"fixed":"2.6.0"}],"type":"SEMVER"}],"versions":[]}],"fixed_versions":[{"source":"GitHub Advisory Database","source_url":"https://github.com/advisories/GHSA-6rvj-qwjf-3m4q","source_modified_at":"2026-10-09T20:51:07Z","fetched_at":"2026-10-23T18:42:43.628194Z","package":{"ecosystem":"go","name":"code.vikunja.io/api"},"version":"2.6.0"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-91972","source_modified_at":"2026-09-17T15:12:40.377Z","fetched_at":"2026-10-23T18:45:31.882637Z","package":{"name":"vikunja","ecosystem":null},"version":"2.6.0","basis":"first unaffected version stated in the CVE record"},{"source":"OSV","source_url":"https://osv.dev/vulnerability/GHSA-6rvj-qwjf-3m4q","source_modified_at":"2026-10-19T21:41:17.124911538Z","fetched_at":"2026-10-23T18:42:43.628194Z","package":{"ecosystem":"Go","name":"code.vikunja.io/api","purl":"pkg:golang/code.vikunja.io/api"},"version":"2.6.0"}],"cvss":8.7,"severity":"High","kev":{"listed":false},"epss":{"probability":0.00633,"percentile":0.49733,"score_date":"2026-10-23"},"published_at":"2026-09-15T15:18:22.792Z","modified_at":"2026-10-19T21:41:17.124911538Z","provenance":[{"source":"GitHub Advisory Database","url":"https://github.com/advisories/GHSA-6rvj-qwjf-3m4q","fetched_at":"2026-10-23T18:42:43.628194Z","source_modified_at":"2026-10-09T20:51:07Z"},{"source":"CVE List","url":"https://www.cve.org/CVERecord?id=CVE-2026-91972","fetched_at":"2026-10-23T18:45:31.882637Z","source_modified_at":"2026-09-17T15:12:40.377Z"},{"source":"OSV","url":"https://osv.dev/vulnerability/GHSA-6rvj-qwjf-3m4q","fetched_at":"2026-10-23T18:42:43.628194Z","source_modified_at":"2026-10-19T21:41:17.124911538Z"},{"source":"EPSS","url":"https://api.first.org/data/v1/epss?cve=CVE-2026-91972","fetched_at":"2026-10-23T18:42:43.628194Z","source_modified_at":"2026-10-23"}],"sources":["GitHub Advisory Database","CVE List","OSV","EPSS"],"references":[{"source":"CVE List","url":"https://github.com/go-vikunja/vikunja/security/advisories/GHSA-6rvj-qwjf-3m4q","tags":["exploit"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-91972","source":"GitHub Advisory Database"},{"url":"https://github.com/go-vikunja/vikunja/releases/tag/v2.6.0","source":"GitHub Advisory Database"},{"source":"CVE List","url":"https://www.vulncheck.com/advisories/vikunja-before-2.6.0-authentication-bypass-via-unthrottled-api","tags":["third-party-advisory"]},{"url":"https://github.com/advisories/GHSA-6rvj-qwjf-3m4q","source":"GitHub Advisory Database"}],"locations":[],"motoko_assessment":{"status":"requires_architecture_review","automatic_remediation":false},"cve_state":"PUBLISHED","ssvc":{"exploitation":"poc","automatable":"yes","technical_impact":"partial","assessed_at":"2026-09-17T15:11:53.582933Z"},"classification":{"method":"product-first software-layer rules","rules_version":"2.1","matched_on":"ecosystem","confidence":"heuristic","reviewed":false},"change_timestamp":"2026-10-19T21:41:17.124911538Z","content_hash":"ac7bac493e268ad4ea7d829aa1a8156e77f86f4e3dff156ca8ed79fd2e3c27ac"}}