CVE-2025-65318Public exploitNetwork attack vector

Attachment protection bypass via missing Mark-of-the-Web

Published Dec 16, 2025 · Updated Dec 16, 2025

Protection mechanism failure in Canary Mail 5.1.40 and earlier allows remote attackers to bypass Windows attachment safeguards. The attachment interaction path writes files selected through Open with or Save as without applying the Mark-of-the-Web tag that signals untrusted origin. A recipient must open or save a crafted attachment; the bypass removes Windows and third-party file protections, while code execution requires a separate flaw in the attachment handler.

CVSS severity9.1
Critical
EPSS probability0.56%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Protection mechanism failure in Canary Mail 5.1.40 and earlier allows remote attackers to bypass Windows attachment safeguards. The attachment interaction path writes files selected through Open with or Save as without applying the Mark-of-the-Web tag that signals untrusted origin. A recipient must open or save a crafted attachment; the bypass removes Windows and third-party file protections, while code execution requires a separate flaw in the attachment handler.

The record

CVE
CVE-2025-65318
Published
Dec 16, 2025
Updated
Dec 16, 2025
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-693, T1204.002
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 16, 2025CVE publishedPublication date reported by the CVE source.
  2. Dec 16, 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?

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

9.1CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

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-693Protection Mechanism Failure
T1204.002User Execution: Malicious File

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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