CVE-2021-45946

Application crash via unused compiler-slot sentinel

Published Dec 31, 2021 · Updated Aug 4, 2024

Out-of-bounds write in CompileBlock in Wasm3 0.5.0 allows local users to crash an application by loading crafted WebAssembly. When restoring block parameters to the compiler stack, CompileBlock can pass the c_slotUnused sentinel from GetSlotForStackIndex to MarkSlotsAllocatedByType, which writes outside the slot table. A user must cause an application embedding Wasm3 to compile a crafted module; the documented consequence is a process crash.

CVSS severity5.5
Medium
EPSS probability0.66%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds write in CompileBlock in Wasm3 0.5.0 allows local users to crash an application by loading crafted WebAssembly. When restoring block parameters to the compiler stack, CompileBlock can pass the c_slotUnused sentinel from GetSlotForStackIndex to MarkSlotsAllocatedByType, which writes outside the slot table. A user must cause an application embedding Wasm3 to compile a crafted module; the documented consequence is a process crash.

The record

CVE
CVE-2021-45946
Published
Dec 31, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-787, T1204.002
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 31, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

4.3NIST NVDAV:N/AC:M/Au:N/C:N/I:N/A:P
5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-787Out-of-bounds Write
T1204.002User Execution: Malicious File

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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