{"id":"GHSA-qv2r-v3mx-f4pf","summary":"zebrad has full node denial of service via non-ASCII LongPollId in getblocktemplate","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's 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's `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.","aliases":["CVE-2026-52731"],"modified":"2026-07-02T19:41:33.465493Z","published":"2026-07-02T19:28:03Z","database_specific":{"github_reviewed":true,"github_reviewed_at":"2026-07-02T19:28:03Z","nvd_published_at":null,"cwe_ids":["CWE-248"],"severity":"MODERATE"},"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"}],"affected":[{"package":{"name":"zebra-rpc","ecosystem":"crates.io","purl":"pkg:cargo/zebra-rpc"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"8.0.0"}]}],"database_specific":{"last_known_affected_version_range":"\u003c= 7.0.0","source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/07/GHSA-qv2r-v3mx-f4pf/GHSA-qv2r-v3mx-f4pf.json"}},{"package":{"name":"zebrad","ecosystem":"crates.io","purl":"pkg:cargo/zebrad"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"4.5.0"}]}],"database_specific":{"last_known_affected_version_range":"\u003c= 4.4.1","source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/07/GHSA-qv2r-v3mx-f4pf/GHSA-qv2r-v3mx-f4pf.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H"}]}