Data race and double free via unsound `Send`/`Sync` in `reblessive`
Published Sources: OSV
What is affected, what to do
`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.
The available sources name no fixed version. Check the vendor guidance and the linked original advisory.
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Metrics
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XIEM Effective CVSS
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CVSS v3
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EPSS score
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- Severity
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Priority (0–325)
The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first?
Read in glossary- 30.00 Methodology
Exploit maturity
An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack.
Read in glossary- no public PoC known
KEV status
The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.
Read in glossary- —
- Published
Classification under NIS2 and CRA
Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.
NIS2
NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management.
Read in glossary- Handle the vulnerability in regular vulnerability handling under Art. 21(2)(e) NIS2.
CRA
The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates.
Read in glossary- From 11.12.2027, Annex I Part II CRA requires manufacturers of affected products with digital elements to handle vulnerabilities without delay and provide security updates.
ISO/IEC 27001
ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security.
Read in glossary- Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.
Description
`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. 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`).