symfony/ux-live-component: LiveComponentHydrator HMAC checksum lacks component and slot binding
The advisory, in context
Description
In symfony/ux-live-component, a component's server-side state is exposed to the browser as a set of props (#[LiveProp]-annotated properties). Props marked writable: true can be freely changed by the client. Read-only props are round-tripped to the browser and back, and their integrity is protected by an HMAC so the client cannot tamper with them. Child components additionally receive a propsFromParent blob, also HMAC-signed.
The HMAC computed by Symfony\UX\LiveComponent\LiveComponentHydrator covered only the sorted prop key/value pairs. It didn't include the component name, the slot identifier (props vs propsFromParent), or any request context, and a single application-wide secret is used for every component. A signed blob the server minted for component A is therefore a valid signature for component B if the key names happen to match, and a props blob can be replayed in the propsFromParent slot (or the reverse). An attacker can use this to set a read-only prop on a target component to a value they were only ever allowed to choose as a writable prop on another component.
Resolution
The HMAC is now bound to its context: the component name and a slot identifier are included in the pre-image before hashing. Two constants (CHECKSUM_SLOT_PROPS and CHECKSUM_SLOT_PROPS_FROM_PARENT) name the two slots, and calculateChecksum(), verifyChecksum(), addChecksumToData(), and ChildComponentPartialRenderer thread these values through. Cross-component and cross-slot replays no longer verify.
The patch for this issue is available here for branch 2.x (and forward-ported to 3.x).
Credits
Symfony would like to thank Anthropic (via Project Glasswing) for reporting the issue and Hugo Alliaume for providing the fix.
Affected packages
Start with the recorded fix for your release branch. Check your installed version and test compatibility before upgrading. Fixing this advisory does not rule out other vulnerabilities in the release.
From 2.8.0 before 2.36.0
Fixed in 2.36.0
47 explicitly affected versions
v2.10.0, v2.11.0, v2.11.1, v2.11.2, v2.12.0, v2.13.0, v2.13.1, v2.13.2, v2.13.3, v2.14.0, v2.14.1, v2.14.2, v2.15.0, v2.16.0, v2.17.0, v2.18.0, v2.18.1, v2.19.0, v2.19.2, v2.20.0, v2.21.0, v2.22.0, v2.22.1, v2.23.0, v2.24.0, v2.25.0, v2.25.1, v2.25.2, v2.26.0, v2.26.1, v2.27.0, v2.28.0, v2.28.1, v2.28.2, v2.29.0, v2.29.1, v2.29.2, v2.30.0, v2.31.0, v2.32.0, v2.33.0, v2.34.0, v2.35.0, v2.8.0, v2.8.1, v2.9.0, v2.9.1
View affected-version evidence
{
"ranges": [
{
"events": [
{
"introduced": "2.8.0"
},
{
"fixed": "2.36.0"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"v2.10.0",
"v2.11.0",
"v2.11.1",
"v2.11.2",
"v2.12.0",
"v2.13.0",
"v2.13.1",
"v2.13.2",
"v2.13.3",
"v2.14.0",
"v2.14.1",
"v2.14.2",
"v2.15.0",
"v2.16.0",
"v2.17.0",
"v2.18.0",
"v2.18.1",
"v2.19.0",
"v2.19.2",
"v2.20.0",
"v2.21.0",
"v2.22.0",
"v2.22.1",
"v2.23.0",
"v2.24.0",
"v2.25.0",
"v2.25.1",
"v2.25.2",
"v2.26.0",
"v2.26.1",
"v2.27.0",
"v2.28.0",
"v2.28.1",
"v2.28.2",
"v2.29.0",
"v2.29.1",
"v2.29.2",
"v2.30.0",
"v2.31.0",
"v2.32.0",
"v2.33.0",
"v2.34.0",
"v2.35.0",
"v2.8.0",
"v2.8.1",
"v2.9.0",
"v2.9.1"
]
}From 3.0.0 before 3.1.0
Fixed in 3.1.0
1 explicitly affected versions
v3.0.0
View affected-version evidence
{
"ranges": [
{
"events": [
{
"introduced": "3.0.0"
},
{
"fixed": "3.1.0"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"v3.0.0"
]
}