How severe is GHSA-4m4j-hmqq-3gxm?

No CVSS score has been assigned to GHSA-4m4j-hmqq-3gxm yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by GHSA-4m4j-hmqq-3gxm?

GHSA-4m4j-hmqq-3gxm affects the following packages: symfony/ux-live-component (Packagist), symfony/ux-live-component (Packagist). Ecosystems affected: Packagist.

How do I fix GHSA-4m4j-hmqq-3gxm?

Update symfony/ux-live-component to 2.36.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-4m4j-hmqq-3gxm is resolved across your whole dependency graph.

How do I detect GHSA-4m4j-hmqq-3gxm in my Packagist dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for symfony/ux-live-component, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate GHSA-4m4j-hmqq-3gxm if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

How does O3 Security protect against GHSA-4m4j-hmqq-3gxm?

O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like GHSA-4m4j-hmqq-3gxm can be triaged on real exposure rather than presence alone.

Is GHSA-4m4j-hmqq-3gxm actively exploited in the wild?

No public exploit code has been indexed for GHSA-4m4j-hmqq-3gxm yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for GHSA-4m4j-hmqq-3gxm?

GHSA-4m4j-hmqq-3gxm has an EPSS (Exploit Prediction Scoring System) score of 0.2%, placing it in the 8th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is GHSA-4m4j-hmqq-3gxm?

GHSA-4m4j-hmqq-3gxm is classified as Cross-Site Request Forgery (CSRF) (CWE-352). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was GHSA-4m4j-hmqq-3gxm published, and has it been updated?

GHSA-4m4j-hmqq-3gxm was published on June 19, 2026 and was last updated on September 10, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐘 Packagist

Not in CISA KEV

GHSA-4m4j-hmqq-3gxm — symfony/ux-live-component

Fix: symfony/ux@aed7493

GHSA-4m4j-hmqq-3gxm is a Cross-Site Request Forgery (CSRF) vulnerability in symfony/ux-live-component. A fix is available for symfony/ux-live-component — see the affected versions and patch details below.

symfony/ux-live-component: CSRF Protection Bypass — Accept Header is CORS-Safelisted

Also known asCVE-2026-49215

Published

Jun 19, 2026

Updated

Sep 10, 2026

Affected

2 pkgs

Patched

2 / 2

Exploits

None indexed

Exploitation data as of Sep 17, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for GHSA-4m4j-hmqq-3gxm.

EPSS Exploitation Probability

via FIRST.org ↗

0.2%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs8th percentile — riskier than 8% of all scored CVEsHighest risk

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

Real-World Exposure

2 pkgs affected

🐘symfony/ux-live-component🐘symfony/ux-live-component

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.

Description

When using symfony/ux-live-component, methods annotated with #[LiveAction] are invokable from the browser and mutate server-side state via AJAX. Symfony\UX\LiveComponent\EventListener\LiveComponentSubscriber::isLiveComponentRequest() gated these invocations on the presence of Accept: application/vnd.live-component+html, with a code comment stating that this acted as a CSRF protection.

The Accept header is a CORS-safelisted request header, so a cross-origin fetch() can set it without triggering a preflight. The header therefore provided no CSRF protection. Any #[LiveAction] could be forged cross-origin against a victim's session.

In practice the attack is mitigated by SameSite=Lax session cookies (Symfony's default), but applications using SameSite=None, credentials: 'include' with a permissive cookie policy, or that have been pivoted from another same-origin vector remained exposed.

Resolution

isLiveComponentRequest() now additionally requires the request header X-Requested-With: XMLHttpRequest. This header is not CORS-safelisted, so the browser issues a preflight OPTIONS request for any cross-origin attempt; Symfony does not advertise CORS for LiveComponent endpoints, the preflight fails, and the real request is blocked before it reaches the application. The bundled Stimulus client already sends X-Requested-With on every LiveComponent request (RequestBuilder.ts), so standard usage is unaffected. Cross-origin callers must add X-Requested-With to their CORS Access-Control-Allow-Headers allow-list.

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

2 total 2 fixed

Ecosystem	Package	Vulnerable range	Fix
🐘Packagist	`symfony/ux-live-component`	≥ 2.22.0&&< 2.36.0	2.36.0`composer require symfony/ux-live-component:^2.36.0`
🐘Packagist	`symfony/ux-live-component`	≥ 3.0.0&&< 3.1.0	3.1.0`composer require symfony/ux-live-component:^3.1.0`

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for symfony/ux-live-component, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update symfony/ux-live-component to 2.36.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-4m4j-hmqq-3gxm is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like GHSA-4m4j-hmqq-3gxm can be triaged on real exposure rather than presence alone.

Tailored to GHSA-4m4j-hmqq-3gxm. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

### Description When using `symfony/ux-live-component`, methods annotated with `#[LiveAction]` are invokable from the browser and mutate server-side state via AJAX. `Symfony\UX\LiveComponent\EventListener\LiveComponentSubscriber::isLiveComponentRequest()` gated these invocations on the presence of `Accept: application/vnd.live-component+html`, with a code comment stating that this acted as a CSRF protection. The `Accept` header is a [CORS-safelisted request header](https://fetch.spec.whatwg.org/#cors-safelisted-request-header), so a cross-origin `fetch()` can set it without triggering a pref

O3 Security · Impact-Aware SCA

Is GHSA-4m4j-hmqq-3gxm in your dependencies?

O3 Security finds GHSA-4m4j-hmqq-3gxm across Packagist dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.

Scan my dependencies How O3 SCA works

GHSA-4m4j-hmqq-3gxm — symfony/ux-live-component

Exploitation Status

No confirmed exploitation observed yet

EPSS Exploitation Probability

Real-World Exposure

Description

Description

Resolution

Credits

Affected Packages

Detection & mitigation playbook

Detect

Fix

Workarounds

How O3 protects you

Frequently Asked Questions

Is GHSA-4m4j-hmqq-3gxm in your dependencies?