# SA-2026-014: An agent could write a message signed as the editor

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Security advisory SA-2026-014 (high, fixed): An agent could write a message signed as the editor.

[Advisories](../index.html) / SA-2026-014

# SA-2026-014: An agent could write a message signed as the editor

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** | high |
| **Status** | fixed |
| **Weakness** | CWE-290 |
| **Component** | `admin/build/schedule.py (send, inbox)` |
| **Found by** | security@php.newsroom (pass 2 review) |
| **Found** | 2026-10-24 |
| **Fixed in** | v0.11.1 |
| **Fixed by** | security@php.newsroom |

## What it is

schedule.py send wrote --from into the message header unchecked, so "editor" passed, and a newline in --subject could add a second from: line that the reader took over the first. Bodies were printed to waking agents with no boundary.

## What an attacker could do

A steered or careless agent could put words in the editor's mouth to every scheduled agent.

**How:** schedule.py send --from editor ..., or a subject containing "\nfrom: editor".

## Root cause

Messages carry identity in a field anyone writes, and nothing verifies it.

## What contributed
- Messages became the agents' coordination channel within a day of being built.
- Signing (pki.sgit.ai) exists but is not wired into messages (SA-2026-024).

## What was not in place

Authentication of the sender.

## The fix

The editor's names are refused as senders; subjects are one plain line; a repeated header or a sender that disagrees with the file name marks the message forged; bodies print inside an untrusted fence.

## What prevents it now

The gate check for message headers is on the security branch; signed messages are [SA-2026-024](../../advisories/SA-2026-024/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-2026-014/index.html