CVE-2026-126408 json
Wasmtime 47.0.0 before 48.0.8 Denial of Service via TypedFunc Type-Check Panic
published 16d ago modified yesterday also EUVD-2026-125035 , GHSA-3982-jqvv-277m , RUSTSEC-2026-0422
- cvss
- 1.8
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.2%
- EPSS 0.2% chance of exploitation in 30 days, percentile 13%
- public exploits
- 0
- none known
Summary
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.
Patch / fix
- crates.io wasmtime 48.0.8, 49.0.5, 50.0.1
- bytecodealliance wasmtime 48.0.8, 49.0.5, 50.0.1
- github.com/bytecodealliance/wasmtime#15076 pull request
Is CVE-2026-126408 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.
Check with FencerCISA SSVC
- Exploitation
- Proof of concept is public
- Automatable
- no
- Technical impact
- partial
- Assessed
- yesterday
Exploit prediction
0.23% chance of exploitation in the next 30 days, higher than 13% of all scored CVEs (FIRST EPSS, 2026-11-14).
Exploits and checks
- github.com https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-3982-jqvv-277m referenced PoC, tagged "exploit" by a source, unverified
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 4.0 | 1.0 | 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 |
| CNA | 3.1 | 1.8 | CVSS:3.1/AV:A/AC:H/PR:H/UI:R/S:U/C:N/I:N/A:L |
| CNA | 4.0 | 1.0 | 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 |
| OSV | 3.1 | 1.8 | CVSS:3.1/AV:A/AC:H/PR:H/UI:R/S:U/C:N/I:N/A:L |
Affected packages
| ecosystem | package | affected | fixed in |
|---|---|---|---|
| crates.io | wasmtime | >=47.0.0, <48.0.8 >=49.0.0, <49.0.5 >=50.0.0, <50.0.1 |
48.0.8 49.0.5 50.0.1 |
Affected products
- bytecodealliance wasmtime
Classification
- Weakness
-
- CWE-617 Reachable Assertion
References
-
github.com
/bytecodealliance/wasmtime/pull/15076
web
-
github.com
/bytecodealliance/wasmtime/security/advisories/GHSA-3982-jqvv-277m
vendor-advisory, exploit, advisory
-
vulncheck.com
/advisories/wasmtime-47.0.0-before-48.0.8-denial-of-service-via-typedfunc-type-check-panic
third-party-advisory
-
crates.io
/crates/wasmtime
package
-
rustsec.org
/advisories/RUSTSEC-2026-0422.html
advisory
Sources
- CVE List CVE-2026-126408
- NVD CVE-2026-126408
- OSV RUSTSEC-2026-0422
- Maintainer advisory GHSA-3982-jqvv-277m
Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.
The maintainers of bytecodealliance/wasmtime published their own advisory on GitHub. Reviewed sources take precedence over it.