CVE-2026-27572Network attack vector

Host process crash via excessive WASI HTTP fields

Published Feb 24, 2026 · Updated Feb 24, 2026

Denial of service in Bytecode Alliance Wasmtime allows attackers to crash an embedding host through excessive WASI HTTP fields. The wasi:http/types.fields implementation in the wasmtime-wasi-http crate adds guest-controlled headers to a capacity-limited backing map without converting its capacity panic into a guest trap. Exploitation requires untrusted WebAssembly guest code to reach the WASI HTTP fields interface; the resulting panic terminates the embedder process rather than affecting confidentiality or integrity.

CVSS severity6.9
Medium
EPSS probability0.47%
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 Bytecode Alliance Wasmtime allows attackers to crash an embedding host through excessive WASI HTTP fields. The wasi:http/types.fields implementation in the wasmtime-wasi-http crate adds guest-controlled headers to a capacity-limited backing map without converting its capacity panic into a guest trap. Exploitation requires untrusted WebAssembly guest code to reach the WASI HTTP fields interface; the resulting panic terminates the embedder process rather than affecting confidentiality or integrity.

The record

CVE
CVE-2026-27572
Published
Feb 24, 2026
Updated
Feb 24, 2026
Vendor
Bytecode Alliance
Product
Wasmtime
Classifications
CWE-770, T1499.004
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=< 24.0.6
  2. Affected versionversion=>= 25.0.0, < 36.0.6
  3. Affected versionversion=>= 37.0.0, < 40.0.4
  4. Affected versionversion=>= 41.0.0, < 41.0.4

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Bytecode Alliance · Wasmtimeversion=< 24.0.6; version=>= 25.0.0, < 36.0.6; version=>= 37.0.0, < 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:L/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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

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 exploitUnconfirmed

Weakness, pattern, technique

CWE-770Allocation of Resources Without Limits or Throttling
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

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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