CVE-2022-40957Network attack vector

Crash via incoherent WebAssembly instruction cache

Published Dec 22, 2022 · Updated Apr 15, 2025

WebAssembly cache incoherence in Firefox before 105, Firefox ESR before 102.3, and Thunderbird before 102.3 allows remote attackers to crash them. The ARM64 WebAssembly JIT can publish newly compiled code to another thread without a context-synchronization operation, leaving stale instruction-cache data executable. Exploitation requires an ARM64 build and attacker-controlled WebAssembly; Thunderbird email reading disables scripting, limiting reachability to browser-like contexts.

CVSS severity6.5
Medium
EPSS probability1.08%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

WebAssembly cache incoherence in Firefox before 105, Firefox ESR before 102.3, and Thunderbird before 102.3 allows remote attackers to crash them. The ARM64 WebAssembly JIT can publish newly compiled code to another thread without a context-synchronization operation, leaving stale instruction-cache data executable. Exploitation requires an ARM64 build and attacker-controlled WebAssembly; Thunderbird email reading disables scripting, limiting reachability to browser-like contexts.

The record

CVE
CVE-2022-40957
Published
Dec 22, 2022
Updated
Apr 15, 2025
Vendor
Mozilla
Product
Firefox
Classifications
CWE-240, T1499.004, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 22, 2022CVE publishedPublication date reported by the CVE source.
  2. Apr 15, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=unspecified <105

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Mozilla · Firefoxversion=unspecified <105
Mozilla · Thunderbirdversion=unspecified <102.3
Mozilla · Firefox ESRversion=unspecified <102.3

Published CVSS scores

6.5NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
6.5CISA-ADPCVSS:3.1/AV:N/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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

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

Weakness, pattern, technique

CWE-240Improper Handling of Inconsistent Structural Elements
T1499.004Application or System Exploitation
T1203Exploitation for Client Execution

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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