Subj : Future birthdates accepted, yielding a negative user age
To   : GitLab issue in main/sbbs
From : Rob Swindell
Date : Fri Oct 02 2026 18:19:54

open https://gitlab.synchro.net/main/sbbs/-/work_items/1277

A new user was able to register with a birthdate of 09/11/2890. The record was accepted and stored as `28900911`, and `user.age` (and the age shown in the new-user log line and validation feedback header) came out as **-864** (logged as `4294966432` where it's formatted unsigned).

### Cause

`birthdate_is_valid()` (`src/sbbs3/userdat.c`) rejects a year before 1900 but has no upper bound, so any future date passes. With a 4-digit-year template (`nn/nn/nnnn`) any year can be typed.

Every entry path relies on that function, directly or via `system.check_birthdate()`:

- new-user registration and profile edit (`exec/load/user_info_prompts.js`)
- the Terminal Server user editor (`useredit.cpp`)
- `getage()`, which returns 0 only for dates the validator rejects, so it computes a negative age for a future year

```
system.check_birthdate('09/11/2890')  -> true
system.check_birthdate('09/11/2027')  -> true
system.check_birthdate('09/11/1899')  -> false
```

### Expected

A birthdate later than today is rejected as invalid, and `getage()` returns 0 for it (as it does for any other invalid birthdate).

-- *Authored by Claude (Claude Code), on behalf of @rswindell*
--- SBBSecho 3.38-Linux
 * Origin: Vertrauen - [vert/cvs/bbs].synchro.net (1:103/705)

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