CVE-2026-126407

Wasmtime before 36.0.20 Denial of Service via Borrowed Resource Transfer

Published Nov 13, 2026 CVSS 4.0 · 5.9 Medium EPSS n/a KEV · Not listed

Description

Wasmtime before 36.0.20, 37.0.0 before 48.0.8, 49.0.0 before 49.0.5, and 50.0.0 before 50.0.1 allocates untracked host memory when a component receives a borrow of a resource it defines itself, bypassing the per-store handle limit. A malicious guest component can repeatedly transfer such borrowed resources to consume arbitrary host memory, causing denial of service.

Affected Products

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions

bytecodealliance

wasmtime

unaffected

Version	Status	Constraints
`0`	affected	< 36.0.20
`36.0.20`	unaffected	—

bytecodealliance

wasmtime

unaffected

Version	Status	Constraints
`37.0.0`	affected	< 48.0.8
`48.0.8`	unaffected	—

bytecodealliance

wasmtime

unaffected

Version	Status	Constraints
`49.0.0`	affected	< 49.0.5
`49.0.5`	unaffected	—

bytecodealliance

wasmtime

unaffected

Version	Status	Constraints
`50.0.0`	affected	< 50.0.1
`50.0.1`	unaffected	—

No data.

No data available yet.

Remediation

No solution or workaround provided in the CVE record

Tracking

Advisories

No advisories available

Metrics

Attack Vector Network

Attack Complexity Low

Privileges Required Low

Attack Requirements Present

User Interaction Passive

Vulnerable System Confidentiality Impact None

Vulnerable System Integrity Impact None

Vulnerable System Availability Impact High

Subsequent System Confidentiality Impact None

Subsequent System Integrity Impact None

Subsequent System Availability Impact None

Attack Vector Network

Attack Complexity High

Privileges Required Low

Scope Unchanged

Confidentiality Impact None

Integrity Impact None

Availability Impact High

User Interaction Required

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

No EPSS score available.

Key SSVC decision points have not yet been added.

References

Link	Providers
https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-6fr9-xmw9-5352
https://www.vulncheck.com/advisories/wasmtime-before-36.0.20-denial-of-service-via-borrowed-resource-transfer

History

Nov 13, 2026 9:45 AM Description updated. Title updated. First appearance in the feed. Weaknesses updated. Affected versions updated. Affected vendors updated. Added references. Scoring metrics updated View changes

Type	Values Removed	Values Added
Description		Wasmtime before 36.0.20, 37.0.0 before 48.0.8, 49.0.0 before 49.0.5, and 50.0.0 before 50.0.1 allocates untracked host memory when a component receives a borrow of a resource it defines itself, bypassing the per-store handle limit. A malicious guest component can repeatedly transfer such borrowed resources to consume arbitrary host memory, causing denial of service.
Title		Wasmtime before 36.0.20 Denial of Service via Borrowed Resource Transfer
First Time appeared		Bytecodealliance Bytecodealliance wasmtime
Weaknesses		CWE-770
CPEs		cpe:2.3:a:bytecodealliance:wasmtime::::::::
Vendors & Products		Bytecodealliance Bytecodealliance wasmtime
References		https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-6fr9-xmw9-5352 https://www.vulncheck.com/advisories/wasmtime-before-36.0.20-denial-of-service-via-borrowed-resource-transfer
Metrics		cvssV3_1 `{'score': 4.8, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:N/I:N/A:H'}` cvssV4_0 `{'score': 5.9, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N'}`