CVE-2024-9400Public exploitNetwork attack vector

Memory corruption via missed JIT allocation failure

Published Oct 1, 2024 · Updated Oct 1, 2024

Memory corruption in Firefox before 131, Firefox ESR before 128.3, and Thunderbird before 128.3 or 131 allows remote attackers to corrupt memory. IonAnalysis failed to propagate allocation failures while marking MIR operands as implicitly used, leaving compiler objects in an unexpected state. Exploitation requires interaction with attacker-controlled content and an out-of-memory event at one precise point during Ion JIT compilation; Mozilla reports no practical way to force that isolated condition.

CVSS severity8.8
High
EPSS probability0.51%
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 Firefox before 131, Firefox ESR before 128.3, and Thunderbird before 128.3 or 131 allows remote attackers to corrupt memory. IonAnalysis failed to propagate allocation failures while marking MIR operands as implicitly used, leaving compiler objects in an unexpected state. Exploitation requires interaction with attacker-controlled content and an out-of-memory event at one precise point during Ion JIT compilation; Mozilla reports no practical way to force that isolated condition.

The record

CVE
CVE-2024-9400
Published
Oct 1, 2024
Updated
Oct 1, 2024
Vendor
Mozilla
Product
Firefox
Classifications
CWE-119, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Oct 1, 2024CVE publishedPublication date reported by the CVE source.
  2. Oct 1, 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?

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

  1. Affected versionversion=0 <131
  2. Affected versionversion=unspecified <131

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Mozilla · Firefoxversion=0 <131; version=unspecified <131
Mozilla · Thunderbirdversion=0 <128.3; version=0 <131; version=unspecified <128.3; version=unspecified <131
Mozilla · Firefox ESRversion=0 <128.3; version=unspecified <128.3

Published CVSS scores

8.8CISA-ADPCVSS: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.

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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)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-119Improper Restriction of Operations within the Bounds of a Memory Buffer
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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