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CVE-2026-27572— Wasmtime can panic when adding excessive fields to a `wasi:http/types.fields` instance

Quick assessment

Affected
bytecodealliance wasmtime
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

wasmtime是Bytecode Alliance开源的一个轻量级WebAssembly运行时。 Wasmtime 24.0.6之前版本、36.0.6之前版本、4.0.04之前版本、41.0.4之前版本和42.0.0之前版本存在安全漏洞，该漏洞源于wasi:http/types.fields资源实现在添加过多标头字段时容易发生崩溃，可能导致拒绝服务攻击。

AI Predicted 7.5 Difficulty: Easy EPSS 0.66% · P50

Possible ATT&CK Techniques 1 AI

T1499 · Endpoint Denial of Service
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I. Basic Information for CVE-2026-27572

Vulnerability Information
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Vulnerability Title
Wasmtime can panic when adding excessive fields to a `wasi:http/types.fields` instance
Source: CVE Program / CVE List V5
Vulnerability Description
Wasmtime is a runtime for WebAssembly. Prior to versions 24.0.6, 36.0.6, 4.0.04, 41.0.4, and 42.0.0, Wasmtime's implementation of the `wasi:http/types.fields` resource is susceptible to panics when too many fields are added to the set of headers. Wasmtime's implementation in the `wasmtime-wasi-http` crate is backed by a data structure which panics when it reaches excessive capacity and this condition was not handled gracefully in Wasmtime. Panicking in a WASI implementation is a Denial of Service vector for embedders and is treated as a security vulnerability in Wasmtime. Wasmtime 24.0.6, 36.0.6, 40.0.4, 41.0.4, and 42.0.0 patch this vulnerability and return a trap to the guest instead of panicking. There are no known workarounds at this time. Embedders are encouraged to update to a patched version of Wasmtime.
Source: CVE Program / CVE List V5
CVSS Information
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
Source: CVE Program / CVE List V5
Vulnerability Type
不加限制或调节的资源分配
Source: CVE Program / CVE List V5
Vulnerability Title
wasmtime 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
wasmtime是Bytecode Alliance开源的一个轻量级WebAssembly运行时。 Wasmtime 24.0.6之前版本、36.0.6之前版本、4.0.04之前版本、41.0.4之前版本和42.0.0之前版本存在安全漏洞，该漏洞源于wasi:http/types.fields资源实现在添加过多标头字段时容易发生崩溃，可能导致拒绝服务攻击。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
bytecodealliance wasmtime < 24.0.6 -

II. Public POCs for CVE-2026-27572

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III. Intelligence Information for CVE-2026-27572

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Patches & Fixes for CVE-2026-27572 (1)

Vendor Advisories for CVE-2026-27572 (1)

Same Patch Batch · bytecodealliance · 2026-02-24 · 3 CVEs total

CVE-2026-27195 Wasmtime is vulnerable to panic when dropping a `[Typed]Func::call_async` future
CVE-2026-27204 Wasmtime WASI implementations are vulnerable to guest-controlled resource exhaustion

IV. Related Vulnerabilities

Same product: wasmtime
Same vendor: bytecodealliance
Same weakness: CWE-770

V. Comments for CVE-2026-27572

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