{"id":"RUSTSEC-2026-0435","summary":"Unbounded memory allocation in `thrift` binary protocol `read_bytes`","details":"Affected versions of the `thrift` crate size a buffer directly from an attacker-controlled 4-byte length read off the wire, before reading any payload and with no upper bound, allowing a hostile peer to force a large eager allocation or an immediate abort (denial of service, CWE-400 / CWE-789). This is the Rust implementation's instance of the CVE-2020-13949 pattern, published by the Apache Thrift PMC as CVE-2026-43868.\n\n## Details\n\nIn `TBinaryInputProtocol::read_bytes` (`src/protocol/binary.rs`), the length is read as a `i32` from the transport and cast straight to `usize` to size a zeroing buffer **before** any payload is read:\n\n```rust\nfn read_bytes(&mut self) -\u003e crate::Result\u003cVec\u003cu8\u003e\u003e {\n    let num_bytes = self.transport.read_i32::\u003cBigEndian\u003e()? as usize; // length from the wire\n    let mut buf = vec![0u8; num_bytes];                               // unbounded eager allocation\n    self.transport.read_exact(&mut buf).map(|_| buf).map_err(From::from)\n}\n```\n\nThere is no check that `num_bytes` is non-negative or that it fits within the data actually available:\n\n- A length of `0x7FFFFFFF` forces a ~2 GiB allocation; `0x20000000` forces 512 MiB; and so on, from only a 4-byte input.\n- A negative length casts to a huge `usize` (up to `usize::MAX`), causing an immediate allocation failure / abort.\n\n`read_string` routes through `read_bytes`, so string fields are affected the same way. The sink is reachable from any peer sending binary-protocol data, so this is an unauthenticated, network-reachable denial of service.\n\n## The fix\n\nFrom `thrift` 0.23.0 onward, `read_bytes` goes through `read_binary_len`, which rejects negative sizes and enforces `TConfiguration::max_string_size` (default 100 MiB), alongside default message, frame, and recursion limits.\n\nA separate, related gap on the non-strict message-name path was published as CVE-2026-58389 and fixed in 0.24.0; this advisory covers the `read_bytes` unbounded allocation (CVE-2026-43868), fixed in 0.23.0.","aliases":["BIT-thrift-2026-43868","CVE-2026-43868","GHSA-2f9f-gq7v-9h6m"],"modified":"2026-11-02T12:10:42.318149664Z","published":"2026-11-02T12:00:00Z","database_specific":{"license":"CC0-1.0"},"references":[{"type":"PACKAGE","url":"https://crates.io/crates/thrift"},{"type":"ADVISORY","url":"https://rustsec.org/advisories/RUSTSEC-2026-0435.html"},{"type":"WEB","url":"https://lists.apache.org/thread/zj76dtwnbbs1m7z3focf4wd51pqpsmn9"}],"affected":[{"package":{"name":"thrift","ecosystem":"crates.io","purl":"pkg:cargo/thrift"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0.0.0-0"},{"fixed":"0.23.0"}]}],"ecosystem_specific":{"affected_functions":null,"affects":{"os":[],"functions":["thrift::protocol::binary::TBinaryInputProtocol::read_bytes","thrift::protocol::binary::TBinaryInputProtocol::read_string"],"arch":[]}},"database_specific":{"informational":null,"source":"https://github.com/rustsec/advisory-db/blob/osv/crates/RUSTSEC-2026-0435.json","categories":["denial-of-service"],"cvss":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"}}],"schema_version":"1.9.2","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"}]}