# SA-2026-001: Captured page titles could close the JSON-LD script block and run on the site

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Security advisory SA-2026-001 (high, fixed): Captured page titles could close the JSON-LD script block and run on the site.

[Advisories](../index.html) / SA-2026-001

# SA-2026-001: Captured page titles could close the JSON-LD script block and run on the site

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-79 |
| **Component** | `admin/build/build.py (layout)` |
| **Found by** | security@php.newsroom |
| **Found** | 2026-10-22 |
| **Fixed in** | v0.5.5 |
| **Fixed by** | security@php.newsroom |

## What it is

Every page carries structured data in a  block. Its headline and description came from page titles, and on source pages those titles are the titles of captured third-party pages. They were serialised with json.dumps, which does not escape "
## What an attacker could do

A publisher whose page title held "..." would have run script on every source page of the site, once a collector captured it. No title did; the flaw was latent.

**How:** Publish a page with a crafted ; wait for a collector to capture it; the export copies the title into data/sources.json; the build writes it raw into the JSON-LD block.

## Root cause

Data was serialised for JSON, not for JSON inside HTML. Two contexts, one encoder.

## What contributed
- Five places built  blocks from data; one of them (the feed viewer config) already escaped "
## What was not in place

A single helper for JSON inside , and a gate check that every JSON script block parses.

## The fix

J() escapes "" and "&" in all JSON script blocks.

## What prevents it now

The gate fails on any JSON script block that does not parse or contains "

References: `admin/build/build.py J()`, `admin/build/security_check.py`


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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-2026-001/index.html