php-unserialize-audit

php-unserialize-audit is a command for Claude Code from califio/skills. It costs 134 tokens per session (8,018 once invoked), scanned A, original, MIT.

A security audit command for PHP code that turns and restores stored PHP data, a process called deserialization. It focuses on bugs that can affect memory and object lifetimes during that process.

In plain words
What is it for?
Use it to inspect PHP extensions, files, classes, or deserialization categories for issues such as use-after-free, type confusion, and memory overflows.
Why use it?
It helps security researchers examine a specialised PHP attack surface instead of searching the whole PHP engine without a defined focus.

Command for Claude Code

Written for Claude Code: argument-hint in frontmatter. Also seen: mentions subagents.

Part of the php-unserialize-audit plugin — 1 skill, 1 command shipped together

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add commands/califio/skills/php-unserialize-audit
Clone the repo
git clone --depth 1 https://github.com/califio/skills

Made for: Claude Code.

Or install php-unserialize-audit, the plugin that ships this one along with the rest of its 1 skill, 1 command.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for php-unserialize-audit

README.md
[![agentmods](https://agentmods.dev/badge/commands/califio/skills/php-unserialize-audit.svg)](https://agentmods.dev/commands/califio/skills/php-unserialize-audit)
Your own site
<a href="https://agentmods.dev/commands/califio/skills/php-unserialize-audit"><img src="https://agentmods.dev/badge/commands/califio/skills/php-unserialize-audit.svg" alt="Measured on agentmods" height="20"></a>
Per session 134 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 8,018 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00134 $0.08018
Opus 5 $0.00067 $0.04009
Sonnet 5 $0.00027 $0.01604
Haiku 4.5 $0.00013 $0.00802

Measured 6d ago against content hash c5848e0bcade, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-05, from the pricing page.

Security

Grade A, and why

php-unserialize-audit scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 6d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

plugins/php-unserialize-audit/commands/php-unserialize-audit.md · 479 lines

How it starts

The opening of the file, as written. The whole thing — 479 lines — stays where its author put it; the contents beside it link to each section on GitHub.

PHP Unserialize Surface Audit

Purpose: find exploitable bugs in PHP's deserialization surface and related object-lifetime code that is reachable through deserialization. For general PHP engine memory-safety bugs outside the deserialization flow (e.g. the extract() callback-reentrancy UAF, array_walk callback mutations, generic hash-slot UAFs), use the companion /php-audit skill.

The advisory corpus at work/phpcodz/research/pch-0{10,11,14,15,19,20,21,22,25,26,27,28,29,30,31,32,33,34}.md is the ground truth for what "exploitable" looks like here — re-read one or two before starting if you are unfamiliar.

Usage

/php-unserialize-audit <target> [focus]

Target can be:

  • an extension name: spl, date, gmp, soap, session, phar, standard, sqlite3, pdo, intl, wddx
  • a specific file: ext/spl/spl_array.c, ext/standard/var_unserializer.re
  • a class/subsystem: SplObjectStorage, SoapFault, Exception::getTraceAsString
  • a broad category: unserialize, session-deserializer, magic-methods, custom-unserializers, all

Examples:

  • /php-unserialize-audit spl
  • /php-unserialize-audit unserialize "UAF via R: back-references"
  • /php-unserialize-audit ext/date/php_date.c
  • /php-unserialize-audit session "multi-entry decode UAF"
  • /php-unserialize-audit magic-methods "type confusion in __toString"
  • /php-unserialize-audit all "double-free"

Source tree

PHP sources live at /home/x/kernel/php_old/work/src/php-<version>/. The primary target versions are PHP 5.4.x–5.6.x (matches the advisory corpus), but the same bug classes appear in PHP 7.x with different zval layout. Check which version the user intends; if unspecified, default to php-5.5.14 (the version most PoCs target). Extract the tarball if no extracted tree exists:

cd /home/x/kernel/php_old/work/src && tar xzf php-5.5.14.tar.gz

Bug taxonomy (derived from phpcodz corpus)

Every class below has at least one confirmed instance in the advisory corpus. Use this as the hunting checklist. For each finding, map it to a U-class so the synthesis pass can deduplicate.

Read the full file on GitHub · 479 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 6d ago First seen · 479 lines · 0 tokens per session scan A c5848e0bcade

Subscribe to this mod's changes

php-unserialize-audit is a command published in the GitHub repository califio/skills (59 stars, last pushed 4mo ago), licensed MIT. It adds 134 tokens to every session and 8,018 once invoked, about $0.0007 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.