CVE-2026-275726.9MediumCWE-770

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

bytecodealliance · wasmtime

Affected: bytecodealliance wasmtime · Exploitation: unlikely (under 1%)

Not in CyberSIXT coverage yet: no article names this CVE. This page shows the public record.

0.5%probability of exploitation in the next 30 days

44th percentile

050100

Higher than 44% of scored CVEs

6.9MediumCVSS 4.0

LowMediumHighCrit.

DescriptionCVE.org

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.

Affected products1

From the CVE record. A product or version that is not listed is unknown, not unaffected.

bytecodealliance · wasmtime< 24.0.6; >= 25.0.0, < 36.0.6; >= 37.0.0, < 40.0.4; >= 41.0.0, < 41.0.4

On the Atlas

Every published CVE is on the CyberSIXT Atlas, grouped by weakness, vendor and month.

Open the Atlas

Exploitation: Unlikely (under 1%). EPSS under 1%, or no score yet.
CISA KEV: Not listed
Public check: No public nuclei template
Weakness: Allocation Without Limits · Denial of Service
Vendor: bytecodealliance
Published: February 2026
Band: Unlikely (under 1%), February 2026

CoverageNo articles yet

No CyberSIXT article names CVE-2026-27572 yet, so there is no coverage timeline, action brief or change log for it. Everything on this page comes from the public CVE record, CISA KEV, EPSS and the nuclei template index. Search the archive or see the CVEs in the news.