CVE-2022-38478Public exploitNetwork attack vector

Code execution via pointer confusion and worker UAF

Published Dec 22, 2022 · Updated Apr 15, 2025

Memory corruption in Mozilla Firefox before 104, Firefox ESR before 102.2, and Thunderbird before 102.2 allows remote attackers to execute code. One flaw fails to canonicalize attacker-influenced NaN values before JavaScript treats their bit patterns as object pointers; another releases FetchStreamReader callbacks after worker shutdown, risking use after free. Exploitation requires malicious content and user interaction; Thunderbird disables scripting during ordinary mail reading, limiting exposure to browser-like contexts, and the 91.x branches are affected before 91.13.

CVSS severity8.8
High
EPSS probability0.91%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Memory corruption in Mozilla Firefox before 104, Firefox ESR before 102.2, and Thunderbird before 102.2 allows remote attackers to execute code. One flaw fails to canonicalize attacker-influenced NaN values before JavaScript treats their bit patterns as object pointers; another releases FetchStreamReader callbacks after worker shutdown, risking use after free. Exploitation requires malicious content and user interaction; Thunderbird disables scripting during ordinary mail reading, limiting exposure to browser-like contexts, and the 91.x branches are affected before 91.13.

The record

CVE
CVE-2022-38478
Published
Dec 22, 2022
Updated
Apr 15, 2025
Vendor
Mozilla
Product
Firefox
Classifications
CWE-787, 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 <104

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Mozilla · Firefoxversion=unspecified <104
Mozilla · Thunderbirdversion=unspecified <102.2; version=unspecified <91.13
Mozilla · Firefox ESRversion=unspecified <102.2; version=unspecified <91.13

Published CVSS scores

8.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/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 exploitPublished

Weakness, pattern, technique

CWE-787Out-of-bounds Write
T1203Exploitation for Client Execution

Public exploit references

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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