symfony/ux-live-component: Denial of service via unbounded batch action requests

CVE-2026-49209 View on GitHub ↗ View on CVE.org ↗ View on NVD ↗

Description

Description

Symfony\UX\LiveComponent\Controller\BatchActionController::__invoke() iterates over the client-supplied actions array and issues a full HttpKernel sub-request for each entry (event subscribers, validators, Doctrine, rendering). The array size is never bounded, so an authenticated client can submit a single _batch request containing thousands of actions and exhaust CPU, memory, and database connections on the application server.

Resolution

BatchActionController now enforces an upper bound of 50 actions per _batch request (MAX_ACTIONS_PER_BATCH) and rejects larger payloads up front with a BadRequestHttpException. The matching JavaScript backend was also updated to split larger client-side batches into multiple requests so legitimate usage isn't affected.

The patch for this issue is available here for branch 2.x (and forward-ported to 3.x).

Credits

Symfony would like to thank Pascal Cescon for reporting the issue and Hugo Alliaume for providing the fix.

Basic information

Type
reviewed
Severity
low
Advisory on GitHub
Open advisory ↗
Repository advisory
Open repository advisory ↗
Source code
Browse source ↗
Published (advisory)
2026-06-19 19:34:45 UTC
Updated
2026-06-19 19:34:46 UTC
GitHub reviewed
2026-06-19 19:34:45 UTC

EPSS Score

No EPSS score in this advisory JSON.

CVSS Scores

Base score Version Severity Vector
1.3 4.0 —
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network.
Attack complexity (AC:L)
Exploitation conditions are straightforward and stable.
Attack requirements (AT:N)
No additional preconditions are required beyond normal reachability.
Privileges required (PR:L)
Low privileges are required.
User interaction (UI:N)
No user interaction is required.
Vulnerable system confidentiality impact (VC:N)
No confidentiality impact on the vulnerable system.
Vulnerable system integrity impact (VI:N)
No integrity impact on the vulnerable system.
Vulnerable system availability impact (VA:L)
Limited availability impact on the vulnerable system.
Subsequent system confidentiality impact (SC:N)
No confidentiality impact on subsequent systems.
Subsequent system integrity impact (SI:N)
No integrity impact on subsequent systems.
Subsequent system availability impact (SA:N)
No availability impact on subsequent systems.
Exploit maturity (threat) (E:U)
Unreported: no public PoC, no reported exploitation, and no known simplification tools.

Identifiers

Type Value
GHSA GHSA-mm82-c99c-h2cf ↗
CVE CVE-2026-49209 ↗

CWEs

CWE id Name
CWE-770 Allocation of Resources Without Limits or Throttling

Credits

  • Amoifr (reporter)
  • Kocal (remediation_developer)

Affected packages (2)

Vulnerable version ranges and first patched releases as published by GitHub.

Ecosystem Package Vulnerable range First patched Vulnerable functions
composer symfony/ux-live-component >= 2.5.0, < 2.36.0 2.36.0 —
composer symfony/ux-live-component >= 3.0.0, < 3.1.0 3.1.0 —

References

cvelogic Threat Intelligence