GHSA-QV2R-V3MX-F4PF

Vulnerability from github – Published: 2026-07-02 19:28 – Updated: 2026-07-02 19:28
VLAI
Summary
zebrad has full node denial of service via non-ASCII LongPollId in getblocktemplate
Details

Am I affected

You are affected if:

  1. You run zebrad up to and including v4.4.1.
  2. Your zebrad.toml sets rpc.listen_addr to a TCP address (RPC server is enabled).
  3. An attacker can authenticate to the RPC endpoint. With the default enable_cookie_auth = true, this requires the attacker to read the .cookie file. With enable_cookie_auth = false, any network client reaching the RPC port can trigger it.

Summary

The getblocktemplate RPC handler panics when parsing a LongPollId parameter that contains non-ASCII (multi-byte UTF-8) characters. The handler performs byte-index string slicing on the user-supplied string, which panics in Rust when a byte index falls within a multi-byte character boundary. Because Zebra's release profile sets panic = "abort", the panic terminates the entire node process.

Details

The getblocktemplate handler receives a user-supplied LongPollId string and slices it at fixed byte offsets to extract the encoded tip hash and tip height. When the string contains multi-byte UTF-8 characters, a byte-index slice can land in the middle of a character, causing Rust's str indexing to panic with "byte index is not a char boundary."

Under the panic = "abort" release profile, this panic terminates the entire zebrad process rather than just the RPC task.

Patches

zebra-rpc 8.0.0 and zebrad 4.5.0.

Replace byte-index string slicing with character-aware parsing or validate that the LongPollId string contains only ASCII characters before slicing.

Workarounds

  • Disable the RPC server by removing rpc.listen_addr from zebrad.toml.
  • Ensure enable_cookie_auth = true (the default) and restrict filesystem access to the .cookie file.
  • Place a reverse proxy in front of the RPC port that validates LongPollId parameters are ASCII-only before forwarding.

Impact

A single authenticated RPC request terminates the zebrad process. Same impact profile as GHSA-c8w6-x74f-vmg3: repeatable on restart, affects mining pools and infrastructure that forward getblocktemplate calls.

Credit

Reported by @sangsoo-osec via a private GitHub Security Advisory submission.

Show details on source website

{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 7.0.0"
      },
      "package": {
        "ecosystem": "crates.io",
        "name": "zebra-rpc"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "8.0.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 4.4.1"
      },
      "package": {
        "ecosystem": "crates.io",
        "name": "zebrad"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "4.5.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-52731"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-248"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-07-02T19:28:03Z",
    "nvd_published_at": null,
    "severity": "MODERATE"
  },
  "details": "### Am I affected\n\nYou are affected if:\n\n1. You run `zebrad` up to and including `v4.4.1`.\n2. Your `zebrad.toml` sets `rpc.listen_addr` to a TCP address (RPC server is enabled).\n3. An attacker can authenticate to the RPC endpoint. With the default `enable_cookie_auth = true`, this requires the attacker to read the `.cookie` file. With `enable_cookie_auth = false`, any network client reaching the RPC port can trigger it.\n\n### Summary\n\nThe `getblocktemplate` RPC handler panics when parsing a `LongPollId` parameter that contains non-ASCII (multi-byte UTF-8) characters. The handler performs byte-index string slicing on the user-supplied string, which panics in Rust when a byte index falls within a multi-byte character boundary. Because Zebra\u0027s release profile sets `panic = \"abort\"`, the panic terminates the entire node process.\n\n### Details\n\nThe `getblocktemplate` handler receives a user-supplied `LongPollId` string and slices it at fixed byte offsets to extract the encoded tip hash and tip height. When the string contains multi-byte UTF-8 characters, a byte-index slice can land in the middle of a character, causing Rust\u0027s `str` indexing to panic with \"byte index is not a char boundary.\"\n\nUnder the `panic = \"abort\"` release profile, this panic terminates the entire `zebrad` process rather than just the RPC task.\n\n### Patches\n\nzebra-rpc 8.0.0 and zebrad 4.5.0.\n\nReplace byte-index string slicing with character-aware parsing or validate that the `LongPollId` string contains only ASCII characters before slicing.\n\n### Workarounds\n\n- Disable the RPC server by removing `rpc.listen_addr` from `zebrad.toml`.\n- Ensure `enable_cookie_auth = true` (the default) and restrict filesystem access to the `.cookie` file.\n- Place a reverse proxy in front of the RPC port that validates `LongPollId` parameters are ASCII-only before forwarding.\n\n### Impact\n\nA single authenticated RPC request terminates the `zebrad` process. Same impact profile as GHSA-c8w6-x74f-vmg3: repeatable on restart, affects mining pools and infrastructure that forward `getblocktemplate` calls.\n\n### Credit\n\nReported by `@sangsoo-osec` via a private GitHub Security Advisory submission.",
  "id": "GHSA-qv2r-v3mx-f4pf",
  "modified": "2026-07-02T19:28:03Z",
  "published": "2026-07-02T19:28:03Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/ZcashFoundation/zebra/security/advisories/GHSA-qv2r-v3mx-f4pf"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/ZcashFoundation/zebra"
    },
    {
      "type": "WEB",
      "url": "https://github.com/ZcashFoundation/zebra/blob/d4cd662c716382f6397d2a730148025a1ca79fec/Cargo.toml#L305"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "zebrad has full node denial of service via non-ASCII LongPollId in getblocktemplate"
}



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