CVE-2025-9187Network attack vector

Arbitrary code execution via memory corruption

Published Aug 19, 2025 · Updated Apr 13, 2026

Memory corruption in Mozilla Firefox and Thunderbird before 142 allows remote attackers to execute arbitrary code via malicious content. The public advisory groups four memory-safety bugs but does not disclose their affected components or the out-of-bounds operations that corrupt memory. Firefox is exposed through browser content; Thunderbird email reading disables scripting, so exposure there requires a browser or browser-like context.

CVSS severity9.8
Critical
EPSS probability0.45%
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 and Thunderbird before 142 allows remote attackers to execute arbitrary code via malicious content. The public advisory groups four memory-safety bugs but does not disclose their affected components or the out-of-bounds operations that corrupt memory. Firefox is exposed through browser content; Thunderbird email reading disables scripting, so exposure there requires a browser or browser-like context.

The record

CVE
CVE-2025-9187
Published
Aug 19, 2025
Updated
Apr 13, 2026
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-119, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 19, 2025CVE publishedPublication date reported by the CVE source.
  2. Apr 13, 2026Record 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 vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

9.8NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/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 exploitUnconfirmed

Weakness, pattern, technique

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