| Package | Affected versions | Patched versions |
|---|---|---|
| code.vikunja.io/api | < 2.6.0all versions | 2.6.0 |
The /dav, /.well-known, and /feeds groups are registered on the root Echo instance with only BasicAuth and no rate limiter. CalDAV BasicAuth accepts the plain account password, so password guessing over /dav is unbounded and never returns 429, while /api/v1/login is throttled from the tenth attempt. The only anti-brute-force control on the instance is therefore bypassable.
pkg/routes/routes.go (~lines 238-249) registers /.well-known, /dav, and /feeds with middleware.BasicAuth(...) and nothing else; registerCalDavRoutes adds no limiter. pkg/routes/caldav/auth.go (~lines 88-93) falls through to user.CheckUserCredentials with the plain account password when no CalDAV token matches. In contrast, /register, /login, etc. are wrapped by unauthRateLimit() — an unconditional 10/min/IP pre-auth floor that ignores ratelimit.enabled (default false).
TOTP-enabled accounts and bot users are correctly refused, so this targets password-only accounts.
POST /api/v1/login x25 wrong passwords -> 429 from attempt 2 (throttled)
PROPFIND /dav/principals/{user}/ x60 wrong passwords -> 401 x60, 429 x0
GET /feeds/notifications.atom x30 wrong passwords -> 401 x30, 429 x0
PROPFIND /dav/... with correct password -> 207 (proves the 401s are real auth failures)
The anti-brute-force floor guarding /login is entirely absent on /dav, /feeds, and /.well-known, giving an unbounded credential-guessing surface against account passwords. (bcrypt caps throughput to a few guesses/second, but nothing caps the number of attempts.) Reported as an authentication-control bypass, not a DoS.
Apply the unconditional pre-auth rate-limit floor to the /dav, /.well-known, and /feeds groups.
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