How severe is GHSA-cq8v-f236-94qc?

No CVSS score has been assigned to GHSA-cq8v-f236-94qc yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by GHSA-cq8v-f236-94qc?

GHSA-cq8v-f236-94qc affects the following packages: rand (crates.io), rand (crates.io), rand (crates.io). Ecosystems affected: crates.io.

How do I fix GHSA-cq8v-f236-94qc?

Update rand to 0.9.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-cq8v-f236-94qc is resolved across your whole dependency graph.

How do I detect GHSA-cq8v-f236-94qc in my crates.io dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for rand. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

How do I mitigate GHSA-cq8v-f236-94qc if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

How does O3 Security protect against GHSA-cq8v-f236-94qc?

O3 pinpoints whether GHSA-cq8v-f236-94qc is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Is GHSA-cq8v-f236-94qc actively exploited in the wild?

No public exploit code has been indexed for GHSA-cq8v-f236-94qc yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

When was GHSA-cq8v-f236-94qc published, and has it been updated?

GHSA-cq8v-f236-94qc was published on April 14, 2026 and was last updated on April 22, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🦀 crates.io

GHSA-cq8v-f236-94qc

Rand is unsound with a custom logger using rand::rng()

Also known asRUSTSEC-2026-0097

Published

Apr 14, 2026

Updated

Apr 22, 2026

Affected

3 pkgs

Patched

3 / 3

Exploits

None indexed

Blast Radius

3 pkgs affected

🦀rand🦀rand🦀rand

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects crates.io packages — download data is not available via public APIs for these ecosystems.

Description

It has been reported (by @lopopolo) that the rand library is unsound (i.e. that safe code using the public API can cause Undefined Behaviour) when all the following conditions are met:

The log and thread_rng features are enabled
A custom logger is defined
The custom logger accesses rand::rng() (previously rand::thread_rng()) and calls any TryRng (previously RngCore) methods on ThreadRng
The ThreadRng (attempts to) reseed while called from the custom logger (this happens every 64 kB of generated data)
Trace-level logging is enabled or warn-level logging is enabled and the random source (the getrandom crate) is unable to provide a new seed

TryRng (previously RngCore) methods for ThreadRng use unsafe code to cast *mut BlockRng<ReseedingCore> to &mut BlockRng<ReseedingCore>. When all the above conditions are met this results in an aliased mutable reference, violating the Stacked Borrows rules. Miri is able to detect this violation in sample code. Since construction of aliased mutable references is Undefined Behaviour, the behaviour of optimized builds is hard to predict.

Affected Packages

3 total 3 fixed

Ecosystem	Package	Vulnerable range	Fix
🦀crates.io	`rand`	≥ 0.9.0&&< 0.9.3	0.9.3
🦀crates.io	`rand`	≥ 0.10.0&&< 0.10.1	0.10.1
🦀crates.io	`rand`	≥ 0.7.0&&< 0.8.6	0.8.6

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for rand. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update rand to 0.9.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-cq8v-f236-94qc is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-cq8v-f236-94qc is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to GHSA-cq8v-f236-94qc. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

It has been reported (by @lopopolo) that the `rand` library is [unsound](https://rust-lang.github.io/unsafe-code-guidelines/glossary.html#soundness-of-code--of-a-library) (i.e. that safe code using the public API can cause Undefined Behaviour) when all the following conditions are met: - The `log` and `thread_rng` features are enabled - A [custom logger](https://docs.rs/log/latest/log/#implementing-a-logger) is defined - The custom logger accesses `rand::rng()` (previously `rand::thread_rng()`) and calls any `TryRng` (previously `RngCore`) methods on `ThreadRng` - The `ThreadRng` (attempts to

O3 Security · Impact-Aware SCA

Is GHSA-cq8v-f236-94qc in your dependencies?

O3 detects GHSA-cq8v-f236-94qc across crates.io dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

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