CVE-2026-126409
Wasmtime 47.0.0 before 48.0.8 Cross-Engine Type Confusion via StructType Supertype
CVE-2026-126409 is a low vulnerability (CVSS 1.8) in Bytecodealliance Wasmtime, published October 29, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.21%, the 10th percentile. Fixed in wasmtime 48.0.8.
- Severity
- 1.8 LowCVSS 4.0, CVE List
- Exploit chance
- 0.21%EPSS, 10th percentile
- Exploitation
- None knownNot on CISA’s or ENISA’s lists
- Fixed in
48.0.8wasmtime +3 more
Description
Wasmtime 47.0.0 before 48.0.8, 49.0.0 before 49.0.5, and 50.0.0 before 50.0.1 contains a cross-engine type confusion vulnerability because StructType::with_finality_and_supertype does not validate that the supplied supertype belongs to the same Engine. Embedders using multiple engines that create a GC struct type with another engine's supertype can trigger runtime panics or GC heap corruption, causing denial of service; guest WebAssembly cannot trigger it.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- High
- Privileges needed
- High
- User interaction
- Active
What an attacker can affect
- Confidentiality
- None
- Integrity
- None
- Availability
- Low
Exploit likelihood
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
wasmtimecrates.io | 47.0.0 up to 48.0.8, 49.0.0 up to 49.0.5, 50.0.0 up to 50.0.1 | 48.0.849.0.550.0.1 |
rust-wasmtimeUbuntu:24.04:LTS | All versions, plus listed versions 10.0.1+dfsg-715.0.1+dfsg-416.0.0+dfsg-216.0.0+dfsg-3 | None known |
rust-wasmtimeUbuntu:26.10 | All versions, plus listed versions 36.0.5+dfsg-136.0.13+dfsg-1 | None known |
rust-wasmtimeUbuntu:26.04:LTS | All versions, plus listed versions 26.0.1+dfsg-326.0.1+dfsg-428.0.1+dfsg-329.0.1+dfsg-536.0.5+dfsg-1 | None known |
What each source reports
CVE List Score used
Wasmtime 47.0.0 before 48.0.8 Cross-Engine Type Confusion via StructType Supertype
Wasmtime 47.0.0 before 48.0.8, 49.0.0 before 49.0.5, and 50.0.0 before 50.0.1 contains a cross-engine type confusion vulnerability because StructType::with_finality_and_supertype does not validate that the supplied supertype belongs to the same Engine. Embedders using multiple engines that create a GC struct type with another engine's supertype can trigger runtime panics or GC heap corruption, causing denial of service; guest WebAssembly cannot trigger it.
- Record
CVE-2026-126409- CVSS 4.0
- 1.8 Low
CVSS:4.0/AV:N/AC:H/AT:P/PR:H/UI:A/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N - CVSS 3.1
- 2.0 Low
CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:N/I:N/A:L - Weakness
- CWE-843
- Updated
- 2026-11-13
EUVDEUVD-2026-125034
Wasmtime 47.0.0 before 48.0.8, 49.0.0 before 49.0.5, and 50.0.0 before 50.0.1 contains a cross-engine type confusion vulnerability because StructType::with_finality_and_supertype does not validate that the supplied supertype belongs to the same Engine. Embedders using multiple engines that create a GC struct type with another engine's supertype can trigger runtime panics or GC heap corruption, causing denial of service; guest WebAssembly cannot trigger it.
- Record
EUVD-2026-125034- CVSS 4.0
- 1.8 Low
CVSS:4.0/AV:N/AC:H/AT:P/PR:H/UI:A/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N - Updated
- 2026-11-13
GitHub AdvisoriesGHSA-f85g-f2cw-wfg4
Wasmtime 47.0.0 before 48.0.8, 49.0.0 before 49.0.5, and 50.0.0 before 50.0.1 contains a cross...
Wasmtime 47.0.0 before 48.0.8, 49.0.0 before 49.0.5, and 50.0.0 before 50.0.1 contains a cross-engine type confusion vulnerability because StructType::with_finality_and_supertype does not validate that the supplied supertype belongs to the same Engine. Embedders using multiple engines that create a GC struct type with another engine's supertype can trigger runtime panics or GC heap corruption, causing denial of service; guest WebAssembly cannot trigger it.
- Record
GHSA-f85g-f2cw-wfg4- CVSS 4.0
- 1.8 Low
CVSS:4.0/AV:N/AC:H/AT:P/PR:H/UI:A/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - CVSS 3.1
- 2.0 Low
CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:N/I:N/A:L - Weakness
- CWE-843
- Updated
- 2026-11-13
NVD
Wasmtime 47.0.0 before 48.0.8, 49.0.0 before 49.0.5, and 50.0.0 before 50.0.1 contains a cross-engine type confusion vulnerability because StructType::with_finality_and_supertype does not validate that the supplied supertype belongs to the same Engine. Embedders using multiple engines that create a GC struct type with another engine's supertype can trigger runtime panics or GC heap corruption, causing denial of service; guest WebAssembly cannot trigger it.
- Record
CVE-2026-126409- CVSS 4.0
- 1.8 Low
CVSS:4.0/AV:N/AC:H/AT:P/PR:H/UI:A/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - CVSS 3.1
- 2.0 Low
CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:N/I:N/A:L - Weakness
- CWE-843
- Updated
- 2026-11-13
OSV
Wasmtime 47.0.0 before 48.0.8 Cross-Engine Type Confusion via StructType Supertype
Wasmtime 47.0.0 before 48.0.8, 49.0.0 before 49.0.5, and 50.0.0 before 50.0.1 contains a cross-engine type confusion vulnerability because StructType::with_finality_and_supertype does not validate that the supplied supertype belongs to the same Engine. Embedders using multiple engines that create a GC struct type with another engine's supertype can trigger runtime panics or GC heap corruption, causing denial of service; guest WebAssembly cannot trigger it.
- Record
CVE-2026-126409- CVSS 4.0
- 1.8 Low
CVSS:4.0/AV:N/AC:H/AT:P/PR:H/UI:A/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N - Weakness
- CWE-843
- Updated
- 2026-11-14
OSVUBUNTU-CVE-2026-126409
Wasmtime 47.0.0 before 48.0.8, 49.0.0 before 49.0.5, and 50.0.0 before 50.0.1 contains a cross-engine type confusion vulnerability because StructType::with_finality_and_supertype does not validate that the supplied supertype belongs to the same Engine. Embedders using multiple engines that create a GC struct type with another engine's supertype can trigger runtime panics or GC heap corruption, causing denial of service; guest WebAssembly cannot trigger it.
- Record
UBUNTU-CVE-2026-126409- CVSS 4.0
- 1.8 Low
CVSS:4.0/AV:N/AC:H/AT:P/PR:H/UI:A/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N - CVSS 3.1
- 2.0 Low
CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:N/I:N/A:L - Updated
- 2026-11-13
OSVRUSTSEC-2026-0423No score
Cross-engine type confusion with host-created struct-types-with-supertypes
This is an entry in the RustSec database for the Wasmtime security advisory located at https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-qw58-7h65-crq2 For more information see the GitHub-hosted security advisory.
- Record
RUSTSEC-2026-0423- Updated
- 2026-11-14
History
| Recorded | Changed | Sources |
|---|---|---|
| affected, aliases, facts, published, references | OSV | |
| affected, aliases, published, references | OSV | |
| published | EUVD | |
| published | EUVD | |
| aliases, references | GitHub Advisories, NVD | |
| aliases, published | EUVD | |
| first indexed | CVE List | |
| first indexed | OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
References
github.com/bytecodealliance/wasmtime/security/advisories/GHSA-qw58-7h65-crq2
vulncheck.com/advisories/wasmtime-47.0.0-before-48.0.8-cross-engine-type-confusion-via-structtype-supertype
nvd.nist.gov/vuln/detail/CVE-2026-126409
crates.io/crates/wasmtime