Vulnerability-Lookup

GHSA-38X5-RCV4-XF7X

Vulnerability from github – Published: 2026-06-19 19:34 – Updated: 2026-06-19 19:34

Summary

symfony/ux-live-component: XSS via attacker-controlled child component tag

Details

Description

Symfony\UX\LiveComponent\Util\ChildComponentPartialRenderer::createHtml() interpolates the $childTag argument directly into the HTML output as a tag name, without escaping or validation. The value originates from client-controlled JSON (children[id].tag) parsed by LiveComponentSubscriber and propagated through InterceptChildComponentRenderSubscriber, so an attacker who can reach the Live Component endpoint can inject arbitrary HTML, including <script> tags, on any re-render of a Live Component that contains at least one child component.

In the default configuration, the Live Component endpoint is gated by an Accept: application/vnd.live-component+html request-header check that cannot be set cross-origin without a CORS preflight, so the issue is primarily a defense-in-depth gap. It becomes directly exploitable on applications that have relaxed CORS to allow this header from untrusted origins, or that have been pivoted from another same-origin XSS.

Resolution

ChildComponentPartialRenderer now validates $childTag against a strict HTML tag-name regex before interpolating it, and rejects any value that doesn't match. Anything that wouldn't be a valid HTML tag is dropped before reaching the response.

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.

Severity

5.1 (Medium)


                  
                    CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "package": {
        "ecosystem": "Packagist",
        "name": "symfony/ux-live-component"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "2.8.0"
            },
            {
              "fixed": "2.36.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Packagist",
        "name": "symfony/ux-live-component"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "3.0.0"
            },
            {
              "fixed": "3.1.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-49210"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-79"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-06-19T19:34:49Z",
    "nvd_published_at": null,
    "severity": "MODERATE"
  },
  "details": "### Description\n\n`Symfony\\UX\\LiveComponent\\Util\\ChildComponentPartialRenderer::createHtml()` interpolates the `$childTag` argument directly into the HTML output as a tag name, without escaping or validation. The value originates from client-controlled JSON (`children[id].tag`) parsed by `LiveComponentSubscriber` and propagated through `InterceptChildComponentRenderSubscriber`, so an attacker who can reach the Live Component endpoint can inject arbitrary HTML, including `\u003cscript\u003e` tags, on any re-render of a Live Component that contains at least one child component.\n\nIn the default configuration, the Live Component endpoint is gated by an `Accept: application/vnd.live-component+html` request-header check that cannot be set cross-origin without a CORS preflight, so the issue is primarily a defense-in-depth gap. It becomes directly exploitable on applications that have relaxed CORS to allow this header from untrusted origins, or that have been pivoted from another same-origin XSS.\n\n### Resolution\n\n`ChildComponentPartialRenderer` now validates `$childTag` against a strict HTML tag-name regex before interpolating it, and rejects any value that doesn\u0027t match. Anything that wouldn\u0027t be a valid HTML tag is dropped before reaching the response.\n\nThe patch for this issue is available [here](https://github.com/symfony/ux/commit/fbc5e9a1bda7e4556be21bb1d970f382760ed9a9) for branch 2.x (and forward-ported to 3.x).\n\n### Credits\n\nSymfony would like to thank Pascal Cescon for reporting the issue and Hugo Alliaume for providing the fix.",
  "id": "GHSA-38x5-rcv4-xf7x",
  "modified": "2026-06-19T19:34:49Z",
  "published": "2026-06-19T19:34:49Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/symfony/ux/security/advisories/GHSA-38x5-rcv4-xf7x"
    },
    {
      "type": "WEB",
      "url": "https://github.com/symfony/ux/commit/fbc5e9a1bda7e4556be21bb1d970f382760ed9a9"
    },
    {
      "type": "WEB",
      "url": "https://github.com/FriendsOfPHP/security-advisories/blob/master/symfony/ux-live-component/CVE-2026-49210.yaml"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/symfony/ux"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "symfony/ux-live-component: XSS via attacker-controlled child component tag"
}

CVE-2026-49210 (GCVE-0-2026-49210)

Vulnerability from cvelistv5 – Published: 2026-07-17 16:09 – Updated: 2026-07-17 16:52

Title

Symfony UX: XSS in symfony/ux-live-component via attacker-controlled child component tag

Summary

Symfony UX is a JavaScript ecosystem for Symfony. From 2.8.0 until 2.36.0 and 3.1.0, Symfony\UX\LiveComponent\Util\ChildComponentPartialRenderer::createHtml() interpolates the client-controlled children[id].tag value from LiveComponentSubscriber and InterceptChildComponentRenderSubscriber directly into HTML as a tag name without escaping or validation, allowing arbitrary HTML, including <script> tags, on any Live Component re-render that contains at least one child component. This issue is fixed in versions 2.36.0 and 3.1.0.

Severity

2.3 (Low)


                        
                          CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-07-17 16:52 UTC

CWE

CWE-79 - Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

Assigner

GitHub_M CNA under the mitre root

CNA scorecard C 72/100 over 7613 records in the last 180 days details

References

4 references

URL	Tags
https://github.com/symfony/ux/security/advisories…	x_refsource_CONFIRM
https://github.com/symfony/ux/commit/fbc5e9a1bda7…	x_refsource_MISC
https://github.com/symfony/ux/releases/tag/v2.36.0	x_refsource_MISC
https://github.com/symfony/ux/releases/tag/v3.1.0	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version
symfony	ux	Affected: >= 3.0.0, < 3.1.0 Affected: >= 2.8.0, < 2.36.0

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-49210",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-07-17T16:52:49.114369Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-07-17T16:52:59.836Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "ux",
          "vendor": "symfony",
          "versions": [
            {
              "status": "affected",
              "version": "\u003e= 3.0.0, \u003c 3.1.0"
            },
            {
              "status": "affected",
              "version": "\u003e= 2.8.0, \u003c 2.36.0"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "Symfony UX is a JavaScript ecosystem for Symfony. From 2.8.0 until 2.36.0 and 3.1.0, Symfony\\UX\\LiveComponent\\Util\\ChildComponentPartialRenderer::createHtml() interpolates the client-controlled children[id].tag value from LiveComponentSubscriber and InterceptChildComponentRenderSubscriber directly into HTML as a tag name without escaping or validation, allowing arbitrary HTML, including \u003cscript\u003e tags, on any Live Component re-render that contains at least one child component. This issue is fixed in versions 2.36.0 and 3.1.0."
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "attackComplexity": "LOW",
            "attackRequirements": "PRESENT",
            "attackVector": "NETWORK",
            "baseScore": 2.3,
            "baseSeverity": "LOW",
            "privilegesRequired": "NONE",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "LOW",
            "subIntegrityImpact": "LOW",
            "userInteraction": "PASSIVE",
            "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N",
            "version": "4.0",
            "vulnAvailabilityImpact": "NONE",
            "vulnConfidentialityImpact": "NONE",
            "vulnIntegrityImpact": "NONE"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-79",
              "description": "CWE-79: Improper Neutralization of Input During Web Page Generation (\u0027Cross-site Scripting\u0027)",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-07-17T16:09:59.645Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/symfony/ux/security/advisories/GHSA-38x5-rcv4-xf7x",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/symfony/ux/security/advisories/GHSA-38x5-rcv4-xf7x"
        },
        {
          "name": "https://github.com/symfony/ux/commit/fbc5e9a1bda7e4556be21bb1d970f382760ed9a9",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/symfony/ux/commit/fbc5e9a1bda7e4556be21bb1d970f382760ed9a9"
        },
        {
          "name": "https://github.com/symfony/ux/releases/tag/v2.36.0",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/symfony/ux/releases/tag/v2.36.0"
        },
        {
          "name": "https://github.com/symfony/ux/releases/tag/v3.1.0",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/symfony/ux/releases/tag/v3.1.0"
        }
      ],
      "source": {
        "advisory": "GHSA-38x5-rcv4-xf7x",
        "discovery": "UNKNOWN"
      },
      "title": "Symfony UX: XSS in symfony/ux-live-component via attacker-controlled child component tag"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-49210",
    "datePublished": "2026-07-17T16:09:17.850Z",
    "dateReserved": "2026-05-28T03:42:34.340Z",
    "dateUpdated": "2026-07-17T16:52:59.836Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Vulnerability timeline

Sightings and recorded dates, grouped by day · UTC

Order JSON

Publication & reservation Sightings KEV catalogs Other timestamps

Loading timeline…

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.

Action not permitted