CVE-2026-27195Public exploitNetwork attack vector

Host process crash via dropped asynchronous call futures

Published Feb 24, 2026 · Updated Feb 24, 2026

Denial of service in call_async in Bytecode Alliance Wasmtime 39.0.0 through 40.0.3 and 41.0.0 through 41.0.3 allows attackers to crash the host. The async component call path leaves an instance non-reenterable when a polled future is dropped, then allocates a task and thread before a second call traps; disposing that unfinished task panics. Exploitation requires component-model-async, a yielding guest export, two calls on the same instance, and the embedding to drop both unresolved futures and ignore the intervening trap.

CVSS severity6.9
Medium
EPSS probability0.36%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in call_async in Bytecode Alliance Wasmtime 39.0.0 through 40.0.3 and 41.0.0 through 41.0.3 allows attackers to crash the host. The async component call path leaves an instance non-reenterable when a polled future is dropped, then allocates a task and thread before a second call traps; disposing that unfinished task panics. Exploitation requires component-model-async, a yielding guest export, two calls on the same instance, and the embedding to drop both unresolved futures and ignore the intervening trap.

The record

CVE
CVE-2026-27195
Published
Feb 24, 2026
Updated
Feb 24, 2026
Vendor
Bytecode Alliance
Product
Wasmtime
Classifications
CWE-755, T1499
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Feb 24, 2026CVE publishedPublication date reported by the CVE source.
  2. Feb 24, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=>= 39.0.0, < 40.0.4
  2. Affected versionversion=>= 41.0.0, < 41.0.4

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Bytecode Alliance · Wasmtimeversion=>= 39.0.0, < 40.0.4; version=>= 41.0.0, < 41.0.4

Published CVSS scores

7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
6.9GitHub, Inc.CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-755Improper Handling of Exceptional Conditions
T1499Endpoint Denial of Service

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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