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NVD / CVE Program· CNA VulnCheck

CVE-2026-115391: Wasmtime 46.0.0 before 46.0.3 and 47.0.0 before 47.0.4 Unbounded Heap Allocation via WASIp3 Streams

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: 0.17% (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: bytecodealliance wasmtime 46.0.3, 47.0.4.

Low priority for now. Upgrade to bytecodealliance wasmtime 46.0.3, 47.0.4 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 46.0.0 before 46.0.3 and 47.0.0 before 47.0.4 contains an uncontrolled resource allocation vulnerability in its WASIp3 implementation that buffers guest-specified-length writes on the host without limit. Malicious guests can offer large buffers to WASIp3 file or HTTP write streams, causing the host to copy and buffer all bytes, bounded only by guest linear memory, exhausting host memory.

MediumCVSS 6.9 · v4.0—No exploit Fix available
Published
Oct 22, 2026
Updated
Oct 22, 2026
EPSS
0.1% · 6th percentile

Report tools

JSON

Action score

27

Monitor

Low priority for now.

CVSS
27 / 40 · 6.9 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

CNA vs NVD score

NVD
—
CNA · VulnCheck
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.

Follow CVE-2026-115391

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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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.

—

Versions reported by the vendor

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

  • bytecodealliance wasmtime

    • 46.0.3, 47.0.4not affected
    • 46.0.0 and later · before 46.0.3affected · semver
    • 47.0.0 and later · before 47.0.4affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
crates.iowasmtimefrom 46.0.0 · before 46.0.346.0.3
crates.iowasmtimefrom 47.0.0 · before 47.0.447.0.4

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-2026-115389Oct 22, 2026 · Wasmtime before 36.0.16, 37.0.0 before 48.0.3, and 49.0.0 before 49.0.1 Denial of Service via Val API
    4Monitor
  • ← EarlierCVE-2026-115390Oct 22, 2026 · Wasmtime 47.0.0 before 48.0.3 and 49.0.0 before 49.0.1 Fuel Accounting Bypass DoS
    27Monitor
  • Later →CVE-2026-115392Oct 22, 2026 · Wasmtime before 24.0.13, 25.0.0 before 36.0.14, 37.0.0 before 46.0.3, and 47.0.0 before 47.0.4 Sandbox Escape via Trailing Slashes
    35Monitor

Remediation

Which version to upgrade to

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

Product / packageFixed versionSource
bytecodealliance wasmtime46.0.3Vendor (CNA)
bytecodealliance wasmtime47.0.4Vendor (CNA)
crates.io:wasmtime46.0.3Package registry (OSV)
crates.io:wasmtime47.0.4Package 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.

  1. Published
  2. Fix recordedsame day
  3. TodayNov 2, 2026+11 d
EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

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

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

Variant candidates

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

  • CVE-2026-1191347 days apartWasmtime before 36.0.18, 37.0.0 before 48.0.6, and 49.0.0 before 49.0.3 Unbounded Memory Growth via Component-Model Resource Handles
    27Monitor
  • CVE-2026-27572240 days apartWasmtime can panic when adding excessive fields to a `wasi:http/types.fields` instance
    27Monitor
  • CVE-2026-1153810 days apartWasmtime before 36.0.17, 37.0.0 before 48.0.4, and 49.0.0 before 49.0.2 Unbounded Host Memory Allocation via SinkOutputStream write-zeroes
    23Monitor
  • CVE-2026-44216161 days apartWasmtime: Panic when allocating a table exceeding the size of the host's address space
    23Monitor
  • CVE-2026-1153800 days apartWasmtime before 36.0.17, 37.0.0 before 48.0.4, and 49.0.0 before 49.0.2 Fuel Limit Bypass DoS via WASI Preview 0 poll_oneoff
    20Monitor
  • CVE-2026-1153890 days apartWasmtime before 36.0.16, 37.0.0 before 48.0.3, and 49.0.0 before 49.0.1 Denial of Service via Val API
    4Monitor

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

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-770 · Allocation of Resources Without Limits or Throttling

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

Attack context

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

Change log

  1. Fix✗ → ✓
  2. Exploit maturity— → none

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

References

Show all references (1 more)

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

All records