How severe is GHSA-6wgr-89rj-399p?

No CVSS score has been assigned to GHSA-6wgr-89rj-399p yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by GHSA-6wgr-89rj-399p?

GHSA-6wgr-89rj-399p affects the following packages: wasmtime (crates.io), wasmtime (crates.io), wasmtime (crates.io). Ecosystems affected: crates.io.

How do I fix GHSA-6wgr-89rj-399p?

Update wasmtime to 36.0.7 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-6wgr-89rj-399p is resolved across your whole dependency graph.

How do I detect GHSA-6wgr-89rj-399p in my crates.io dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for wasmtime. 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-6wgr-89rj-399p 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-6wgr-89rj-399p?

O3 pinpoints whether GHSA-6wgr-89rj-399p 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-6wgr-89rj-399p actively exploited in the wild?

No public exploit code has been indexed for GHSA-6wgr-89rj-399p 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.

What type of vulnerability is GHSA-6wgr-89rj-399p?

GHSA-6wgr-89rj-399p is classified as Buffer Overflow (CWE-119). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

When was GHSA-6wgr-89rj-399p published, and has it been updated?

GHSA-6wgr-89rj-399p was published on April 9, 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-6wgr-89rj-399p

GHSA-6wgr-89rj-399p is a Buffer Overflow vulnerability in wasmtime. O3 Security confirms whether GHSA-6wgr-89rj-399p is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.

Wasmtime has data leakage between pooling allocator instances

Also known asCVE-2026-34988RUSTSEC-2026-0088

Published

Apr 9, 2026

Updated

Apr 22, 2026

Affected

3 pkgs

Patched

3 / 3

Exploits

None indexed

Real-World Exposure

3 pkgs affected

🦀wasmtime🦀wasmtime🦀wasmtime

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

Impact

Wasmtime's implementation of its pooling allocator contains a bug where in certain configurations the contents of linear memory can be leaked from one instance to the next. The implementation of resetting the virtual memory permissions for linear memory used the wrong predicate to determine if resetting was necessary, where the compilation process used a different predicate. This divergence meant that the pooling allocator incorrectly deduced at runtime that resetting virtual memory permissions was not necessary while compile-time determine that virtual memory could be relied upon.

Exposing this bug requires specific configuration values to be used. If any of these configurations are not applicable then this bug does not happen:

The pooling allocator must be in use.
The Config::memory_guard_size configuration option must be 0.
The Config::memory_reservation configuration must be less than 4GiB.
The pooling allocator must be configured with max_memory_size the same as the memory_reservation value.

If all of these conditions are applicable then when a linear memory is reused the VM permissions of the previous iteration are not reset. This means that the compiled code, which is assuming out-of-bounds loads will segfault, will not actually segfault and can read the previous contents of linear memory if it was previously mapped.

This represents a data leakage vulnerability between guest WebAssembly instances which breaks WebAssembly's semantics and additionally breaks the sandbox that Wasmtime provides. Wasmtime is not vulnerable to this issue with its default settings, nor with the default settings of the pooling allocator, but embeddings are still allowed to configure these values to cause this vulnerability.

Patches

Wasmtime 36.0.7, 42.0.2, and 43.0.1 have been issued to fix this bug. Users are recommended to update to these patched versions of Wasmtime.

Workarounds

All four conditions above must be met to be vulnerable to this bug, and users can work around this bug by adjusting any of the above conditions. For example it is strongly recommended that guard pages are configured for linear memories which would make this bug not applicable.

Affected Packages

3 total 3 fixed

Ecosystem	Package	Vulnerable range	Fix
🦀crates.io	`wasmtime`	≥ 28.0.0&&< 36.0.7	36.0.7
🦀crates.io	`wasmtime`	≥ 37.0.0&&< 42.0.2	42.0.2
🦀crates.io	`wasmtime`	≥ 43.0.0&&< 43.0.1	43.0.1

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for wasmtime. 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 wasmtime to 36.0.7 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-6wgr-89rj-399p 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-6wgr-89rj-399p 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-6wgr-89rj-399p. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

### Impact Wasmtime's implementation of its pooling allocator contains a bug where in certain configurations the contents of linear memory can be leaked from one instance to the next. The implementation of resetting the virtual memory permissions for linear memory used the wrong predicate to determine if resetting was necessary, where the compilation process used a different predicate. This divergence meant that the pooling allocator incorrectly deduced at runtime that resetting virtual memory permissions was not necessary while compile-time determine that virtual memory could be relied upon.

O3 Security · Impact-Aware SCA

Is GHSA-6wgr-89rj-399p in your dependencies?

O3 detects GHSA-6wgr-89rj-399p 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.

Scan my dependencies How O3 SCA works

GHSA-6wgr-89rj-399p

Real-World Exposure

Description

Impact

Patches

Workarounds

Affected Packages

Detection & mitigation playbook

Detect

Fix

Workarounds

How O3 protects you

Frequently Asked Questions

Is GHSA-6wgr-89rj-399p in your dependencies?