EEx template evaluation of prompt content in AshAi enables remote code execution

{
  "id": "8bd2fd541437e7d9d6c410169538624d291270c42abf2ed65bc2e82e4c38723c",
  "url": "https://osv.dev/vulnerability/CVE-2026-77956",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "EEx template evaluation of prompt content in AshAi enables remote code execution",
    "summary": "Improper Control of Generation of Code (Code Injection) vulnerability in ash-project ash_ai allows a remote, unauthenticated client to execute arbitrary Elixir code. AshAi.Actions.Prompt evaluates prompt content through EEx.eval_string/2. The documented prompt: fn input, context -> ... end form lets the prompt content be built from action arguments, so when a prompt action's text incorporates request data, that attacker-controlled text is compiled and run as an EEx template (Elixir source). Content such as <%= System.cmd(...) %> therefore executes on the server before any model request is made, requiring no authentication beyond reaching a prompt action. The fix stops evaluating function-supplied prompt content as EEx; only statically configured templates are evaluated. This issue affects ash_ai: from 0.1.0 before 1.0.0.",
    "evidence": "osv:CVE-2026-77956",
    "products": [],
    "severity": "high",
    "structured": {
      "id": "CVE-2026-77956",
      "aliases": [
        "CVE-2026-77956",
        "EEF-CVE-2026-77956",
        "GHSA-2g59-hg7m-qc83"
      ],
      "metrics": [
        {
          "type": "CVSS_V4",
          "score": "CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/ash-project/ash_ai",
              "type": "GIT",
              "events": [
                {
                  "introduced": "4aab131d40a0bd5a8cf0b3c4eaaa59d49565f3d1"
                },
                {
                  "fixed": "e9948254b5659c1143b73dc2f59f457931e64514"
                },
                {
                  "introduced": "9be71660e448d601b6b5d1846d227c0b52fb64ac"
                },
                {
                  "fixed": "f72b14744996e71df6d73480d617d963f340597b"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "4aab131d40a0bd5a8cf0b3c4eaaa59d49565f3d1"
                      },
                      {
                        "fixed": "e9948254b5659c1143b73dc2f59f457931e64514"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StandardRange"
                  },
                  {
                    "range": [
                      {
                        "introduced": "0.1.0"
                      },
                      {
                        "fixed": "1.0.0"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StandardRange"
                  },
                  {
                    "range": [
                      {
                        "fixed": "e9948254b5659c1143b73dc2f59f457931e64514"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v0.8.2",
            "v0.8.1",
            "v0.8.0",
            "v0.7.3",
            "v0.7.2",
            "v0.7.1",
            "v0.7.0",
            "v0.6.1",
            "v0.6.0",
            "v0.5.0",
            "v0.4.0",
            "v0.3.0",
            "v0.2.14",
            "v0.2.13",
            "v0.2.12",
            "v0.2.11",
            "v0.2.10",
            "v0.2.9",
            "v0.2.8",
            "v0.2.7",
            "v0.2.6",
            "v0.2.5",
            "v0.2.4",
            "v0.2.3",
            "v0.2.2",
            "v0.2.1",
            "v0.1.11",
            "v0.1.10",
            "v0.1.9",
            "v0.1.8",
            "v0.1.7",
            "v0.1.6",
            "v0.1.5",
            "v0.1.4",
            "v0.1.3",
            "v0.1.2",
            "v0.1.1",
            "v0.1.0"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-77956.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:36.092767981Z",
      "provider": "osv",
      "references": [
        "https://cna.erlef.org/cves/CVE-2026-77956.html",
        "https://github.com",
        "https://osv.dev/vulnerability/EEF-CVE-2026-77956",
        "https://repo.hex.pm",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/77xxx/CVE-2026-77956.json",
        "https://github.com/ash-project/ash_ai/security/advisories/GHSA-2g59-hg7m-qc83",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-77956",
        "https://github.com/ash-project/ash_ai/commit/e9948254b5659c1143b73dc2f59f457931e64514",
        "https://github.com/ash-project/ash_ai"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-94"
        ],
        "cna_assigner": "EEF",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/77xxx/CVE-2026-77956.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-77956",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 503391,
  "published_at": "2026-08-31T00:56:26.44+00:00"
}