CVE-2026-52731

ZEBRA is a Zcash node written entirely in Rust. Prior to 4.5.0, an attacker authenticated to an enabled Zebra RPC endpoint can terminate zebrad by supplying a getblocktemplate LongPollId containing multi-byte UTF-8 characters. In zebra-rpc/src/methods/types/long_poll.rs, LongPollId::from_str originally checked the input byte length and then sliced fixed byte ranges to parse encoded fields. A slice boundary can land inside a multi-byte character and trigger Rust's byte index is not a char boundary panic. Zebra release builds use panic equals abort, so one malformed authenticated RPC request terminates the entire node process and can be repeated after restart. This issue is fixed in version 4.5.0.

ZEBRA is a Zcash node written entirely in Rust. Prior to 4.5.0, an attacker authenticated to an enabled Zebra RPC endpoint can terminate zebrad by supplying a getblocktemplate LongPollId containing multi-byte UTF-8 characters. In zebra-rpc/src/methods/types/long_poll.rs, LongPollId::from_str originally checked the input byte length and then sliced fixed byte ranges to parse encoded fields. A slice boundary can land inside a multi-byte character and trigger Rust's byte index is not a char boundary panic. Zebra release builds use panic equals abort, so one malformed authenticated RPC request terminates the entire node process and can be repeated after restart. This issue is fixed in version 4.5.0.

### 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.

### 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.

ZEBRA es un nodo Zcash escrito completamente en Rust. Antes de la versión 4.5.0, un atacante autenticado en un endpoint RPC de Zebra habilitado puede terminar zebrad al proporcionar un LongPollId de getblocktemplate que contiene caracteres UTF-8 multibyte. En zebra-rpc/src/methods/types/long_poll.rs, LongPollId::from_str originalmente verificaba la longitud de los bytes de entrada y luego segmentaba rangos de bytes fijos para analizar campos codificados. Un límite de segmento puede caer dentro de un carácter multibyte y desencadenar el pánico de Rust ’byte index is not a char boundary’. Las compilaciones de lanzamiento de Zebra usan ’panic equals abort’, por lo que una solicitud RPC autenticada malformada termina todo el proceso del nodo y puede repetirse después del reinicio. Este problema está solucionado en la versión 4.5.0.