How severe is GHSA-hx6p-xpx3-jvvv?

GHSA-hx6p-xpx3-jvvv has a CVSS score of 8.1/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by GHSA-hx6p-xpx3-jvvv?

GHSA-hx6p-xpx3-jvvv affects the following packages: wasmtime (crates.io), wasmtime (crates.io), wasmtime (crates.io), wasmtime (crates.io). Ecosystems affected: crates.io.

How do I fix GHSA-hx6p-xpx3-jvvv?

Update wasmtime to 24.0.7 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-hx6p-xpx3-jvvv is resolved across your whole dependency graph.

How do I detect GHSA-hx6p-xpx3-jvvv 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-hx6p-xpx3-jvvv 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-hx6p-xpx3-jvvv?

O3 pinpoints whether GHSA-hx6p-xpx3-jvvv 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-hx6p-xpx3-jvvv actively exploited in the wild?

No public exploit code has been indexed for GHSA-hx6p-xpx3-jvvv 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-hx6p-xpx3-jvvv?

GHSA-hx6p-xpx3-jvvv is classified as Out-of-bounds Read (CWE-125). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was GHSA-hx6p-xpx3-jvvv published, and has it been updated?

GHSA-hx6p-xpx3-jvvv was published on April 9, 2026 and was last updated on May 5, 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-hx6p-xpx3-jvvv

HIGH

GHSA-hx6p-xpx3-jvvv is a high-severity (CVSS 8.1) Out-of-bounds Read vulnerability in wasmtime. O3 Security confirms whether GHSA-hx6p-xpx3-jvvv is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.

Wasmtime: Heap OOB read in component model UTF-16 to latin1+utf16 string transcoding

Also known asCVE-2026-34941RUSTSEC-2026-0093

Published

Apr 9, 2026

Updated

May 5, 2026

Affected

4 pkgs

Patched

4 / 4

Exploits

None indexed

Real-World Exposure

4 pkgs affected

🦀wasmtime🦀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

Summary

Wasmtime contains a vulnerability where when transcoding a UTF-16 string to the latin1+utf16 component-model encoding it would incorrectly validate the byte length of the input string when performing a bounds check. Specifically the number of code units were checked instead of the byte length, which is twice the size of the code units.

This vulnerability can cause the host to read beyond the end of a WebAssembly's linear memory in an attempt to transcode nonexistent bytes. In Wasmtime's default configuration this will read unmapped memory on a guard page, terminating the process with a segfault. Wasmtime can be configured, however, without guard pages which would mean that host memory beyond the end of linear memory may be read and interpreted as UTF-16.

A host segfault is a denial-of-service vulnerability in Wasmtime, and possibly being able to read beyond the end of linear memory is additionally a vulnerability. Note that reading beyond the end of linear memory requires nonstandard configuration of Wasmtime, specifically with guard pages disabled.

Impact

This is an out-of-bounds memory access. Any user running untrusted wasm components that use cross-component string passing (with UTF-16 source and latin1+utf16 destination encodings) is affected.

With guard pages: Denial of service. The host process crashes with SIGBUS/SIGSEGV.
Without guard pages: Potential information disclosure. The guest can read host memory beyond its linear memory allocation.

Patches

Wasmtime 24.0.7, 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

There is no workaround for this bug. Hosts are recommended to updated to a patched version of Wasmtime.

Affected Packages

4 total 4 fixed

Ecosystem	Package	Vulnerable range	Fix
🦀crates.io	`wasmtime`	all versions	24.0.7
🦀crates.io	`wasmtime`	≥ 25.0.0&&< 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 24.0.7 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-hx6p-xpx3-jvvv 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-hx6p-xpx3-jvvv 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-hx6p-xpx3-jvvv. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

### Summary Wasmtime contains a vulnerability where when transcoding a UTF-16 string to the latin1+utf16 component-model encoding it would incorrectly validate the byte length of the input string when performing a bounds check. Specifically the number of code units were checked instead of the byte length, which is twice the size of the code units. This vulnerability can cause the host to read beyond the end of a WebAssembly's linear memory in an attempt to transcode nonexistent bytes. In Wasmtime's default configuration this will read unmapped memory on a guard page, terminating the process

O3 Security · Impact-Aware SCA

Is GHSA-hx6p-xpx3-jvvv in your dependencies?

O3 detects GHSA-hx6p-xpx3-jvvv 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