CVE-2026-126408
Wasmtime 47.0.0 before 48.0.8 Denial of Service via TypedFunc Type-Check Panic
CVE-2026-126408 is a low vulnerability (CVSS 1.0) 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 0.23%, the 13th percentile. Fixed in wasmtime 48.0.8.
- Severity
- 1.0 LowCVSS 4.0, CVE List
- Exploit chance
- 0.23%EPSS, 13th 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 an insufficient type-check in the TypedFunc embedder API for I31, Option<I31>, and Option<NoneRef> parameter or result types, reaching an unreachable!() path. A malicious guest module exporting a function that uses another anyref-hierarchy type can panic the host embedding, causing denial of service.
Attack profile
How easy it is to exploit
- Attack vector
- Adjacent network
- Complexity
- High
- Privileges needed
- High
- User interaction
- Passive
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 Denial of Service via TypedFunc Type-Check Panic
Wasmtime 47.0.0 before 48.0.8, 49.0.0 before 49.0.5, and 50.0.0 before 50.0.1 contains an insufficient type-check in the TypedFunc embedder API for I31, Option<I31>, and Option<NoneRef> parameter or result types, reaching an unreachable!() path. A malicious guest module exporting a function that uses another anyref-hierarchy type can panic the host embedding, causing denial of service.
- Record
CVE-2026-126408- CVSS 4.0
- 1.0 Low
CVSS:4.0/AV:A/AC:H/AT:P/PR:H/UI:P/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N - CVSS 3.1
- 1.8 Low
CVSS:3.1/AV:A/AC:H/PR:H/UI:R/S:U/C:N/I:N/A:L - Weakness
- CWE-617
- Updated
- 2026-11-13
EUVDEUVD-2026-125035
Wasmtime 47.0.0 before 48.0.8, 49.0.0 before 49.0.5, and 50.0.0 before 50.0.1 contains an insufficient type-check in the TypedFunc embedder API for I31, Option<I31>, and Option<NoneRef> parameter or result types, reaching an unreachable!() path. A malicious guest module exporting a function that uses another anyref-hierarchy type can panic the host embedding, causing denial of service.
- Record
EUVD-2026-125035- CVSS 4.0
- 1.0 Low
CVSS:4.0/AV:A/AC:H/AT:P/PR:H/UI:P/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N - Updated
- 2026-11-13
GitHub AdvisoriesGHSA-h5ch-mmp3-rm7x
Wasmtime 47.0.0 before 48.0.8, 49.0.0 before 49.0.5, and 50.0.0 before 50.0.1 contains an...
Wasmtime 47.0.0 before 48.0.8, 49.0.0 before 49.0.5, and 50.0.0 before 50.0.1 contains an insufficient type-check in the TypedFunc embedder API for I31, Option<I31>, and Option<NoneRef> parameter or result types, reaching an unreachable!() path. A malicious guest module exporting a function that uses another anyref-hierarchy type can panic the host embedding, causing denial of service.
- Record
GHSA-h5ch-mmp3-rm7x- CVSS 4.0
- 1.0 Low
CVSS:4.0/AV:A/AC:H/AT:P/PR:H/UI:P/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
- 1.8 Low
CVSS:3.1/AV:A/AC:H/PR:H/UI:R/S:U/C:N/I:N/A:L - Weakness
- CWE-617
- 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 an insufficient type-check in the TypedFunc embedder API for I31, Option<I31>, and Option<NoneRef> parameter or result types, reaching an unreachable!() path. A malicious guest module exporting a function that uses another anyref-hierarchy type can panic the host embedding, causing denial of service.
- Record
CVE-2026-126408- CVSS 4.0
- 1.0 Low
CVSS:4.0/AV:A/AC:H/AT:P/PR:H/UI:P/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
- 1.8 Low
CVSS:3.1/AV:A/AC:H/PR:H/UI:R/S:U/C:N/I:N/A:L - Weakness
- CWE-617
- Updated
- 2026-11-13
OSV
Wasmtime 47.0.0 before 48.0.8 Denial of Service via TypedFunc Type-Check Panic
Wasmtime 47.0.0 before 48.0.8, 49.0.0 before 49.0.5, and 50.0.0 before 50.0.1 contains an insufficient type-check in the TypedFunc embedder API for I31, Option<I31>, and Option<NoneRef> parameter or result types, reaching an unreachable!() path. A malicious guest module exporting a function that uses another anyref-hierarchy type can panic the host embedding, causing denial of service.
- Record
CVE-2026-126408- CVSS 4.0
- 1.0 Low
CVSS:4.0/AV:A/AC:H/AT:P/PR:H/UI:P/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N - Weakness
- CWE-617
- Updated
- 2026-11-14
OSVRUSTSEC-2026-0422
Typed functions with `i31` or `nullref` arguments may panic due to insufficient type-check
This is an entry in the RustSec database for the Wasmtime security advisory located at https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-3982-jqvv-277m For more information see the GitHub-hosted security advisory.
- Record
RUSTSEC-2026-0422- CVSS 3.1
- 1.8 Low
CVSS:3.1/AV:A/AC:H/PR:H/UI:R/S:U/C:N/I:N/A:L - Updated
- 2026-11-14
OSVUBUNTU-CVE-2026-126408
Wasmtime 47.0.0 before 48.0.8, 49.0.0 before 49.0.5, and 50.0.0 before 50.0.1 contains an insufficient type-check in the TypedFunc embedder API for I31, Option<I31>, and Option<NoneRef> parameter or result types, reaching an unreachable!() path. A malicious guest module exporting a function that uses another anyref-hierarchy type can panic the host embedding, causing denial of service.
- Record
UBUNTU-CVE-2026-126408- CVSS 4.0
- 1.0 Low
CVSS:4.0/AV:A/AC:H/AT:P/PR:H/UI:P/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N - CVSS 3.1
- 1.8 Low
CVSS:3.1/AV:A/AC:H/PR:H/UI:R/S:U/C:N/I:N/A:L - Updated
- 2026-11-13
History
| Recorded | Changed | Sources |
|---|---|---|
| affected, aliases, facts, published, references | NVD, OSV | |
| affected, aliases, published, references | CVE List, 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-3982-jqvv-277m
vulncheck.com/advisories/wasmtime-47.0.0-before-48.0.8-denial-of-service-via-typedfunc-type-check-panic
nvd.nist.gov/vuln/detail/CVE-2026-126408
crates.io/crates/wasmtime