CVE-2024-4774Network attack vector

Unspecified impact via unsafe hash-entry relocation

Published May 14, 2024 · Updated Mar 28, 2025

Undefined behavior in Mozilla Firefox before 126 allows attackers to cause unspecified impact via unspecified vectors. ShmemCharMapHashEntry declares itself movable by memmove even though its Pointer member contains std::atomic storage that is not guaranteed to be trivially copyable, bypassing required move operations. Mozilla has not published a trigger or demonstrated consequence, and its engineers reported that supported compilers made practical exploitation unlikely.

CVSS severity6.5
Medium
EPSS probability0.37%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Undefined behavior in Mozilla Firefox before 126 allows attackers to cause unspecified impact via unspecified vectors. ShmemCharMapHashEntry declares itself movable by memmove even though its Pointer member contains std::atomic storage that is not guaranteed to be trivially copyable, bypassing required move operations. Mozilla has not published a trigger or demonstrated consequence, and its engineers reported that supported compilers made practical exploitation unlikely.

The record

CVE
CVE-2024-4774
Published
May 14, 2024
Updated
Mar 28, 2025
Vendor
Mozilla
Product
Firefox
Classifications
CWE-758
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 14, 2024CVE publishedPublication date reported by the CVE source.
  2. Mar 28, 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 <126

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Mozilla · Firefoxversion=unspecified <126

Published CVSS scores

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

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-758Reliance on Undefined, Unspecified, or Implementation-Defined Behavior

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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