RUSTSEC-2026-0454 (GHSA-M9QR-4RCQ-3JHC)
Vulnerability from osv_rustsec – Published: 2026-11-03 12:00 – Updated: 2026-11-06 15:34 – Source websitedbs::Executor drives every SurrealQL statement through reblessive::tree::TreeStack. In reblessive 0.4.3 the runtime types unconditionally assert Send/Sync (unsafe impl Send/Sync for Stack, TreeStack and Runner), while the public entry points accept any future without a Send bound and store it type-erased in a bump allocator.
Two safe-code consequences follow. First, Runner::step_async/finish_async return driver futures tied to the stack borrow rather than to &mut self, so a driver future can be duplicated; because Stack is Sync those futures are Send, and polling two copies on different threads runs drive_top_task concurrently — racy Cell/UnsafeCell access, double pop_task()/pop_dealloc() (double drop / double free) and a non-atomic Option::take. Second, TreeStack: Send lets safe code move a driver whose type-erased future captures !Send state (Rc, RefCell) to another thread while the creating thread keeps an alias of that state.
No unsafe is needed at the call site. surrealdb-core's own query futures are Send only because of the unsound unsafe impl Send for TreeStack, while the captured &mut tree::Stk is deliberately !Send.
The unsound dependency was removed in 4.0.0 and the parser now uses plain recursion (commit 75407c4bcc).
{
"affected": [
{
"database_specific": {
"categories": [
"thread-safety",
"memory-corruption"
],
"cvss": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H",
"informational": null
},
"ecosystem_specific": {
"affected_functions": null,
"affects": {
"arch": [],
"functions": [],
"os": []
}
},
"package": {
"ecosystem": "crates.io",
"name": "surrealdb-core",
"purl": "pkg:cargo/surrealdb-core"
},
"ranges": [
{
"events": [
{
"introduced": "0.0.0-0"
},
{
"fixed": "4.0.0"
}
],
"type": "SEMVER"
}
],
"versions": []
}
],
"aliases": [
"GHSA-m9qr-4rcq-3jhc"
],
"database_specific": {
"license": "CC0-1.0"
},
"details": "`dbs::Executor` drives every SurrealQL statement through `reblessive::tree::TreeStack`. In `reblessive 0.4.3` the runtime types unconditionally assert `Send`/`Sync` (`unsafe impl Send/Sync for Stack`, `TreeStack` and `Runner`), while the public entry points accept any future without a `Send` bound and store it type-erased in a bump allocator.\n\nTwo safe-code consequences follow. First, `Runner::step_async`/`finish_async` return driver futures tied to the stack borrow rather than to `\u0026mut self`, so a driver future can be duplicated; because `Stack` is `Sync` those futures are `Send`, and polling two copies on different threads runs `drive_top_task` concurrently \u2014 racy `Cell`/`UnsafeCell` access, double `pop_task()`/`pop_dealloc()` (double drop / double free) and a non-atomic `Option::take`. Second, `TreeStack: Send` lets safe code move a driver whose type-erased future captures `!Send` state (`Rc`, `RefCell`) to another thread while the creating thread keeps an alias of that state.\n\nNo `unsafe` is needed at the call site. `surrealdb-core`\u0027s own query futures are `Send` only because of the unsound `unsafe impl Send for TreeStack`, while the captured `\u0026mut tree::Stk` is deliberately `!Send`.\n\nThe unsound dependency was removed in 4.0.0 and the parser now uses plain recursion (commit `75407c4bcc`).",
"id": "RUSTSEC-2026-0454",
"modified": "2026-11-06T15:34:32Z",
"published": "2026-11-03T12:00:00Z",
"references": [
{
"type": "PACKAGE",
"url": "https://crates.io/crates/surrealdb-core"
},
{
"type": "ADVISORY",
"url": "https://rustsec.org/advisories/RUSTSEC-2026-0454.html"
},
{
"type": "WEB",
"url": "https://github.com/surrealdb/surrealdb/commit/75407c4bccc6d6679d7d6e7a18af0065afdded7d"
}
],
"related": [],
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H",
"type": "CVSS_V3"
}
],
"summary": "Data race and double free via unsound `Send`/`Sync` in `reblessive`"
}
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