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NVD / CVE Program· CNA VulnCheck

CVE-2026-115384: Wasmtime 39.0.0 before 48.0.4 and 49.0.0 before 49.0.2 Stack Buffer Overflow

CriticalCVSS 9.4 · v4.0—No exploit Fix available

Noroxi assessment

Priority: Monitor (action score 37/100)

  • 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: 0.31% (FIRST EPSS).
  • Anyone who can reach it over the internet can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: bytecodealliance wasmtime 48.0.4, 49.0.2; azl3 cloud-hypervisor 52.0.152-1 on Azure Linux 3.0 Release Notes; azl3 openvmm 0.1.0-1 on Azure Linux 3.0 Release Notes.

Low priority for now. Upgrade to bytecodealliance wasmtime 48.0.4, 49.0.2; azl3 cloud-hypervisor 52.0.152-1 on Azure Linux 3.0 Release Notes; azl3 openvmm 0.1.0-1 on Azure Linux 3.0 Release Notes 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 39.0.0 before 48.0.4 and 49.0.0 before 49.0.2 contains a stack buffer overflow vulnerability that allows malicious guests to write ~16KB to the native stack via unvalidated async callback result types. Attackers can supply components with mistyped component-model-async callback functions to overwrite return addresses, crashing the host or escaping the sandbox.

Published
Oct 22, 2026
Updated
Oct 29, 2026
EPSS
0.3% · 24th percentile

Report tools

JSON

Action score

37

Monitor

Low priority for now.

CVSS
37 / 40 · 9.4 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.3%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
total

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · VulnCheck
9.4
NVD has not scored this yet; the score shown is the CNA’s.

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/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-2026-115384

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

    • 48.0.4, 49.0.2not affected
    • 39.0.0 and later · before 48.0.4affected · semver
    • 49.0.0 and later · before 49.0.2affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
crates.iowasmtimefrom 39.0.0 · before 48.0.448.0.4
crates.iowasmtimefrom 49.0.0 · before 49.0.249.0.2

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-2026-115382Oct 22, 2026 · Wasmtime 46.0.0 before 48.0.4 and 49.0.0 before 49.0.2 wasi:http Zero Timeout Panic DoS
    23Monitor
  • ← EarlierCVE-2026-115383Oct 22, 2026 · Wasmtime 47.0.0 before 48.0.4 and 49.0.0 before 49.0.2 GC Heap Corruption via Tag Imports
    23Monitor
  • Later →CVE-2026-115385Oct 22, 2026 · Wasmtime 46.0.0 before 48.0.4 and 49.0.0 before 49.0.2 Host Panic via WASIp3 Timestamps
    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 / packageFixed versionSource
bytecodealliance wasmtime48.0.4Vendor (CNA)
bytecodealliance wasmtime49.0.2Vendor (CNA)
azl3 cloud-hypervisor 52.0.152-1 on Azure Linux 3.0Release NotesMicrosoft (MSRC)
azl3 openvmm 0.1.0-1 on Azure Linux 3.0Release NotesMicrosoft (MSRC)
azl3 rust 1.75.0-31 on Azure Linux 3.0Release NotesMicrosoft (MSRC)
azl3 rust 1.96.1-2 on Azure Linux 3.0Release NotesMicrosoft (MSRC)
crates.io:wasmtime48.0.4Package registry (OSV)
crates.io:wasmtime49.0.2Package 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 12, 2026+21 d
EPSS, last 120 days

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

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-2026-1191307 days apartWasmtime before 36.0.18, 37.0.0 before 48.0.6, and 49.0.0 before 49.0.3 HTTP Request Target Smuggling
    8Monitor

Not on record for this CVE: patch commit or PR link · 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 user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
Integrity
Availability
Attack vector
Network
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
X

Weakness class (CWE)

CWE-20 · Improper Input Validation

CVSS vector

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/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. SSVC exploitation— → none
  2. Fix✗ → ✓
  3. 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