NVD / CVE Program· CNA GitHub_M

CVE-2026-27204: Wasmtime WASI implementations are vulnerable to guest-controlled resource exhaustion

MediumCVSS 6.9 · v4.0—No exploit Fix available

Noroxi assessment

Priority: Monitor (action score 27/100)

The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
Probability of exploitation in the next 30 days: 0.40% (FIRST EPSS).
Anyone who can reach it over the internet can trigger it. A low-privileged account is enough. No special conditions are required; it is repeatable.
Fixed version: wasmtime (crates.io) 24.0.6, 36.0.6, 40.0.4; rust-wasmtime (Debian:14) 36.0.6+dfsg-1; zed (openSUSE:Tumbleweed) 1.24.2-1.1.

Low priority for now. Upgrade to wasmtime (crates.io) 24.0.6, 36.0.6, 40.0.4; rust-wasmtime (Debian:14) 36.0.6+dfsg-1; zed (openSUSE:Tumbleweed) 1.24.2-1.1 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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 WASI host interfaces are susceptible to guest-controlled resource exhaustion on the host. Wasmtime did not appropriately place limits on resource allocations requested by the guests. This serves as a Denial of Service vector. Wasmtime 24.0.6, 36.0.6, 40.0.4, 41.0.4, and 42.0.0 have all been released with the fix for this issue. These versions do not prevent this issue in their default configuration to avoid breaking preexisting behaviors. All versions of Wasmtime have appropriate knobs to prevent this behavior, and Wasmtime 42.0.0-and-later will have these knobs tuned by default to prevent this issue from happening. There are no known workarounds for this issue without upgrading. Embedders are recommended to upgrade and configure their embeddings as necessary to prevent possibly-malicious guests from triggering this issue.

Denial of service

Published: Feb 24, 2026
Updated: Jun 17, 2026
EPSS: 0.4% · 35th percentile
CWE: CWE-400

Report tools

JSON

Action score

Monitor

Low priority for now.

CVSS: 27 / 40 · 6.9 / 10
CISA KEV: 0 / 30 · Not listed
EPSS: 0 / 30 · 0.4%

CISA SSVC decision

Exploitation: none
Automatable: no
Technical impact: partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD: —
CNA · GitHub_M: 6.9; NVD has not scored this yet; the score shown is the CNA’s.

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

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

Not in KEV: no record of exploitation in the wild
No public exploit code on record
A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Is your version affected? Check it

Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

Vendor	Product	CPE
bytecodealliance	wasmtime	cpe:2.3:a:bytecodealliance:wasmtime

Versions reported by the vendor

Affected version ranges reported by the assigning authority (GitHub_M). Independent of NVD's CPE analysis and usually ahead of it.

bytecodealliance wasmtime
- < 24.0.6, >= 25.0.0, < 36.0.6, >= 37.0.0, < 40.0.4, >= 41.0.0, < 41.0.4affected

Affected versions · NVD (4)

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

bytecodealliance wasmtimebefore 24.0.6
bytecodealliance wasmtime25.0.0 and later · before 36.0.6
bytecodealliance wasmtime37.0.0 and later · before 40.0.4
bytecodealliance wasmtime41.0.0 and later · before 41.0.4

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

Ecosystem	Package	Affected range	Fix
crates.io	wasmtime	from 0.0.0-0 · before 24.0.6	24.0.6
crates.io	wasmtime	from 25.0.0 · before 36.0.6	36.0.6
crates.io	wasmtime	from 37.0.0 · before 40.0.4	40.0.4
crates.io	wasmtime	from 41.0.0 · before 41.0.4	41.0.4
crates.io	wasmtime	before 24.0.6	24.0.6
Debian:13	rust-wasmtime	from 0	—
Debian:14	rust-wasmtime	before 36.0.6+dfsg-1	36.0.6+dfsg-1
openSUSE:Tumbleweed	zed	before 1.24.2-1.1	1.24.2-1.1

Same product

bytecodealliance: all records

Other highest-scoring records for the same primary product.

CVE-2026-115893Wasmtime: Cranelift backend on aarch64 can jump to incorrect target on large Wasm `br_table` instruction
39Monitor
CVE-2026-115889Wasmtime: Bit-packing in Cranelift compiler causes silent overflow and miscompilation
39Monitor
CVE-2022-39394wasmtime_trap_code C API function has out of bounds write vulnerability
39Monitor

Published before and after this one in the same product

← EarlierCVE-2026-24116Jan 27, 2026 · Wasmtime segfault or unused out-of-sandbox load with f64.copysign operator on x86-64
16Monitor
← EarlierCVE-2026-27195Feb 24, 2026 · Wasmtime is vulnerable to panic when dropping a `[Typed]Func::call_async` future
27Monitor
Later →CVE-2026-27572Feb 24, 2026 · Wasmtime can panic when adding excessive fields to a `wasi:http/types.fields` instance
27Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / package	Fixed version	Source
crates.io:wasmtime	24.0.6	Package registry (OSV)
crates.io:wasmtime	36.0.6	Package registry (OSV)
crates.io:wasmtime	40.0.4	Package registry (OSV)
crates.io:wasmtime	41.0.4	Package registry (OSV)
debian:rust-wasmtime	36.0.6+dfsg-1 · Debian:14	Package registry (OSV)
opensuse:zed	1.24.2-1.1 · openSUSE:Tumbleweed	Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

bytecodealliance/wasmtimePR 12599

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

CVE-2026-115388240 days apartWasmtime before 36.0.16, 37.0.0 before 48.0.3, and 49.0.0 before 49.0.1 Memory Exhaustion DoS via wasmtime-wasi-http Outgoing Body Write
27Monitor
CVE-2026-115390240 days apartWasmtime 47.0.0 before 48.0.3 and 49.0.0 before 49.0.1 Fuel Accounting Bypass DoS
27Monitor
CVE-2026-54786127 days apartWasmtime: Leak in WASIp1 `fd_renumber` implementation
9Monitor

Not on record for this CVE: EPSS history · researcher credit · public bounty program.

Technical details

Attack conditions

Anyone who can reach it over the internet can trigger it.
A low-privileged account is enough.
No special conditions are required; it is repeatable.

If successful

Confidentiality
Integrity
Availability

Attack vector: Network
Attack complexity: Low
Privileges required: Low
User interaction: P
Scope: X

Weakness class (CWE)

CWE-400 · Uncontrolled Resource Consumption

CVSS 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:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

nvd-secondary

Root cause

Code that parses nested structures sets no depth or size limit. A small input can turn into a disproportionate processing load.

The bug in code

The whole CWE-400 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

1function expand(node) {
2  return node.children.map(expand);
3}

Fixed

1const MAX_DEPTH = 32;
2function expand(node, depth = 0) {
3  if (depth > MAX_DEPTH) throw new Error("too deep");
4  return node.children.map((c) => expand(c, depth + 1));
5}

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

Attack patterns (CAPEC)

ATT&CK techniques

Endpoint Denial of ServiceT1499

Change log (1)

Fix✗ → ✓Sep 28, 2026, 10:47 PM UTC

For records you follow, these changes also arrive as notifications. →

References

docs.rs/wasmtime-wasi/latest/wasmtime_wasi/struct.WasiCtxBuilder.html#method.max_random_size

Show all references (6 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

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