DeepChat: Persistent DOM XSS via HTML Entity Encoding in `` SVG Rendering (Bypass of `svgSanitizer.ts`)

{
  "id": "d2524c9451a31902276e6ee3c2e3a06ef59664e385579ef39621a8fdcd0012ed",
  "url": "https://osv.dev/vulnerability/CVE-2026-43900",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "DeepChat: Persistent DOM XSS via HTML Entity Encoding in `` SVG Rendering (Bypass of `svgSanitizer.ts`)",
    "summary": "DeepChat is an open-source artificial intelligence agent platform that unifies models, tools, and agents. Prior to v1.0.4-beta.1, a Cross-Site Scripting (XSS) vulnerability exists due to a discrepancy between the backend validation layer and the frontend browser rendering engine. The SVGSanitizer (src/main/lib/svgSanitizer.ts) restricts script execution by scrubbing javascript: protocols using plain-text regular expressions. However, it fails to account for HTML entity decoding prior to Vue's v-html DOM insertion inside the SvgArtifact.vue component. By feeding an SVG artifact with obfuscated entities (e.g., javascript:alert(1)), an attacker can completely bypass the sanitizer, culminating in arbitrary JavaScript execution when a victim interacts with the rendered SVG Element. This vulnerability is fixed in v1.0.4-beta.1.",
    "evidence": "osv:CVE-2026-43900",
    "products": [],
    "severity": "critical",
    "structured": {
      "id": "CVE-2026-43900",
      "aliases": [
        "CVE-2026-43900",
        "GHSA-7r59-67v3-3mgp"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/thinkinaixyz/deepchat",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "c4ce7be1d3061444362f8b6834a8c57119ae2847"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "1.0.4-beta.1"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StringRangeExpression"
                  },
                  {
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "1.0.4-beta.1"
                      }
                    ],
                    "source": "DESCRIPTION"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v1.0.3",
            "v1.0.3-beta.6",
            "v1.0.3-beta.5",
            "v1.0.3-beta.4",
            "v1.0.3-beta.3",
            "v1.0.3-beta.2",
            "v1.0.3-beta.1",
            "v1.0.2",
            "v1.0.1",
            "v1.0.0",
            "v1.0.0-beta.7",
            "v1.0.0-beta.6",
            "v1.0.0-beta.5",
            "v1.0.0-beta.4",
            "v1.0.0-beta.3",
            "v0.5.6-beta.1",
            "v0.5.6-canary",
            "v0.5.6",
            "v0.5.5",
            "v0.5.3",
            "v0.5.2",
            "v0.5.1",
            "v0.5.0",
            "v0.4.9",
            "v0.4.8",
            "v0.4.6",
            "v0.4.5",
            "workflow-19022687016",
            "v0.4.3",
            "v0.4.2",
            "v0.4.1",
            "v0.4.0",
            "v0.3.9",
            "v0.3.7",
            "v0.3.6",
            "v0.3.5",
            "v0.3.4",
            "v0.3.3",
            "v0.3.2",
            "v0.3.1",
            "v0.3.0",
            "v0.2.9",
            "v0.2.8",
            "v0.2.5",
            "v0.2.4",
            "v0.2.3-1",
            "v0.2.3",
            "v0.2.2",
            "v0.2.1",
            "v0.2.0-1",
            "v0.2.0",
            "v0.1.1",
            "v0.1.0",
            "v0.0.16",
            "v0.0.15",
            "v0.0.14",
            "v0.0.13",
            "v0.0.12",
            "v0.0.10",
            "v0.0.11",
            "v0.0.9",
            "v0.0.7",
            "v0.0.6",
            "v0.0.5",
            "v0.0.3",
            "v0.0.2",
            "v0.0.1"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-43900.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:23.141273684Z",
      "provider": "osv",
      "references": [
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/43xxx/CVE-2026-43900.json",
        "https://github.com/ThinkInAIXYZ/deepchat/security/advisories/GHSA-7r59-67v3-3mgp",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-43900"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-79"
        ],
        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/43xxx/CVE-2026-43900.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-43900",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 489610,
  "published_at": "2026-05-11T21:42:19.927+00:00"
}