Out-of-Bounds Read in unbounded-spsc (CVE-2026-46690)
Summary
Vulnerability in unbounded-spsc (CVE-2026-46690). Risk of unauthorized operations or information disclosure. Exploitable via unsafe.
Original description
The description as published by the source.
Summary
Sender::send in src/lib.rs contains an unsafe block in the DISCONNECTED arm that transmutes a raw pointer (*mut Producer) into the bytes of a value-level Consumer. The author's intent, visible in the surrounding comment at lines 386-390, was a value transmute. The shipped code is one level of indirection off.
The resulting Consumer has its internal Arc::ptr set to the address of the producer field on the Sender, not the real ArcInner>. Every subsequent consumer.try_pop() walks Buffer fields at offsets that lie inside the Sender struct (over send_new, inner) and adjacent memory, an out-of-bounds read. When the fake Consumer is dropped at the end of the unsafe block, its Drop calls Arc::drop_in_place on a non-ArcInner address: it decrements bytes that the type system treats as strong_count: AtomicUsize but that are actually the real Arc::ptr value of the Sender, and at zero count it calls dealloc(Layout::for_value(...)) on an address the allocator never returned.
Reachable from 100% safe Rust through the canonical channel pattern: a tx.send(msg) that races with rx.drop(). This is consistent with the SIGSEGV that issue #3 reports in your own test suite.
Affected code (0.2.0, master at 23a9ce7)
// src/lib.rs:384-401
DISCONNECTED => {
self.inner.counter.store (DISCONNECTED, Ordering::SeqCst);
// We want to guarantee if a message was not received that we get it
// back; since spsc…
Source: GitHub Security Advisories (Global) NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-46690 has been found in unbounded-spsc.
Attackers can target a specific entry point like unsafe over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 5.8/10.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "unbounded-spsc CVE-2026-46690" on the vendor's site.
CVE-2026-46690 (unbounded-spsc) — CWE-125 / CVSS v3 5.8
Attack vector: local / no user interaction
Attack surface: unsafe / DISCONNECTED / producer / Sender
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
Out-of-bounds read (CWE-125) exists in unbounded-spsc. Attackers reach the vulnerable code path via unsafe.
Check the vendor advisory for the affected versions of unbounded-spsc. Attack surface: unsafe / DISCONNECTED / producer / Sender.
Severity: Medium (CVSS 5.8/10). Risk of unauthorized operations or information disclosure.
Update to the patched release per vendor advisory.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'unbounded-spsc' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
grep -r 'unbounded-spsc' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
unbounded-spscを grep し、稼働しているサービス・バージョンを把握する。 -
2Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
References
- advisory nvd.nist.gov
- exploit github.com
- package github.com
- web github.com