CVE-2025-8028Public exploitNetwork attack vector

Content-process code execution via truncated branch address

Published Jul 22, 2025 · Updated Jul 29, 2026

Code execution in Mozilla Firefox and Thunderbird allows remote attackers to run code in the content process via crafted WebAssembly on arm64. The arm64 WebAssembly baseline compiler encodes an out-of-range jump-table label in a 21-bit ADR immediate, truncating the address before indexing and branching. A module with more than 65,520 branch-table entries can redirect the indirect jump into attacker-shaped JIT code; Thunderbird email reading disables scripting, so exposure there requires a browser-like context.

CVSS severity9.8
Critical
EPSS probability0.49%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Code execution in Mozilla Firefox and Thunderbird allows remote attackers to run code in the content process via crafted WebAssembly on arm64. The arm64 WebAssembly baseline compiler encodes an out-of-range jump-table label in a 21-bit ADR immediate, truncating the address before indexing and branching. A module with more than 65,520 branch-table entries can redirect the indirect jump into attacker-shaped JIT code; Thunderbird email reading disables scripting, so exposure there requires a browser-like context.

The record

CVE
CVE-2025-8028
Published
Jul 22, 2025
Updated
Jul 29, 2026
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-1332, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 22, 2025CVE publishedPublication date reported by the CVE source.
  2. Jul 29, 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

9.8CISA-ADPCVSS: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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-1332Improper Handling of Faults that Lead to Instruction Skips
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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