# SA-2026-010: The subscriptions drain stored whatever arrived on a public lane

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Security advisory SA-2026-010 (medium, fixed): The subscriptions drain stored whatever arrived on a public lane.

[Advisories](../index.html) / SA-2026-010

# SA-2026-010: The subscriptions drain stored whatever arrived on a public lane

Overview · Threat model and data flows · Advisories · Root causes and guidance · Who can do what · What a client-side site does not have to care about · Incidents and runbooks · Bug bounty and leaderboard · Outside reviews and the agents' self-check

|  |  |
|---|---|
| **Severity** | medium |
| **Status** | fixed |
| **Weakness** | CWE-20 |
| **Component** | `admin/build/subscriptions_drain.py` |
| **Found by** | security@php.newsroom |
| **Found** | 2026-10-22 |
| **Fixed in** | v0.5.5 |
| **Fixed by** | security@php.newsroom |

## What it is

The lane's append token is public. The drain kept any JSON that decrypted: any keys, any email string, a note of any length. The checks were only in the browser form.

## What an attacker could do

Header injection in mail, prompt injection into the sending agent, and junk in the subscriber list.

**How:** Encrypt a request by hand with the published key and post it, skipping the form.

## Root cause

Validation lived in the client, which an attacker does not have to use.

## What contributed
- Public append tokens are a deliberate design; their consequence had not been carried into the drains.

## What was not in place

Server-side (drain-side) validation of every field.

## The fix

Only the form's fields survive, checked against the site's lists; the note is kept as note_untrusted; floods are held.

## What prevents it now

Every drain treats every row as hostile (REQUIREMENTS.md). What mail it can cause is [SA-2026-027](../../advisories/SA-2026-027/index.html).


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site v0.18.0 · data as of 2026-10-24T16:05Z · vault commit 8c16a64a7cf6 · https://php.oct.2026.newsroom.sgit.ai/admin/appsec/advisories/SA-2026-010/index.html