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CVE.org (no NVD analysis yet)· CNA VulnCheck

CVE-2026-126408: Wasmtime 47.0.0 before 48.0.8 Denial of Service via TypedFunc Type-Check Panic

LowCVSS 1.0 · v4.0—No exploit Fix available

Noroxi assessment

Priority: Monitor (action score 4/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Someone on the same network segment can trigger it. Administrator privileges are required. Special conditions such as timing or configuration are required.
  • Fixed version: bytecodealliance wasmtime 48.0.8, 49.0.5, 50.0.1.

Low priority for now. Upgrade to bytecodealliance wasmtime 48.0.8, 49.0.5, 50.0.1 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org

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.

Published
Nov 13, 2026
Updated
Nov 13, 2026
EPSS
—

Report tools

JSON

Action score

4

Monitor

Low priority for now.

CVSS
4 / 40 · 1.0 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · —

CNA vs NVD score

NVD
—
CNA · VulnCheck
1.0
NVD has not scored this yet; the score shown is the CNA’s.

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

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

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  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

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Follow CVE-2026-126408

When you'll hear from us

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  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

—

Versions reported by the vendor

Affected version ranges reported by the assigning authority (VulnCheck). Independent of NVD's CPE analysis and usually ahead of it.

  • bytecodealliance wasmtime

    • 48.0.8, 49.0.5, 50.0.1not affected
    • 47.0.0 and later · before 48.0.8affected · semver
    • 49.0.0 and later · before 49.0.5affected · semver
    • 50.0.0 and later · before 50.0.1affected · semver

Same product

bytecodealliance: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-115893Wasmtime: Cranelift backend on aarch64 can jump to incorrect target on large Wasm `br_table` instruction
    39Monitor
  • CVE-2026-115889Wasmtime: Bit-packing in Cranelift compiler causes silent overflow and miscompilation
    39Monitor
  • CVE-2022-39394wasmtime_trap_code C API function has out of bounds write vulnerability
    39Monitor

Published before and after this one in the same product

  • ← EarlierCVE-2026-126406Nov 13, 2026 · Wasmtime before 36.0.20 HTTP Request Smuggling via wasi-http p2 Content-Length
    25Monitor
  • ← EarlierCVE-2026-126407Nov 13, 2026 · Wasmtime before 36.0.20 Denial of Service via Borrowed Resource Transfer
    23Monitor
  • Later →CVE-2026-126409Nov 13, 2026 · Wasmtime 47.0.0 before 48.0.8 Cross-Engine Type Confusion via StructType Supertype
    7Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
bytecodealliance wasmtime48.0.8Vendor (CNA)
bytecodealliance wasmtime49.0.5Vendor (CNA)
bytecodealliance wasmtime50.0.1Vendor (CNA)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

  1. Published
  2. Fix recordedsame day
  3. TodayNov 13, 2026same day

Not on record for this CVE: EPSS history · patch commit or PR link · researcher credit · variant or chain candidate · public bounty program.

Technical details

Attack conditions

  • Someone on the same network segment can trigger it.
  • Administrator privileges are required.
  • Special conditions such as timing or configuration are required.

If successful

Confidentiality
Integrity
Availability
Attack vector
Adjacent
Attack complexity
High
Privileges required
High
User interaction
P
Scope
X

Weakness class (CWE)

CWE-617 · Reachable Assertion

CVSS vector

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

nvd-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

References

Show all references (1 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records