Cyber Resilience

CVE-2025-65318

Canarymail Canary Mail ≤ 5.1.40

Public PoC
Published
16 December 2025
Modified
05 July 2026
CVSS Score v3.1 9.1
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
EPSS Score 0.0050 40th percentile
Risk Priority 67 floored blend · peak EPSS

Summary

CVE-2025-65318 is a critical-severity Protection Mechanism Failure (CWE-693) vulnerability in Canarymail Canary Mail. Its CVSS base score is 9.1 (Critical).

Operationally, exploitation aligns with the MITRE ATT&CK technique Abuse Elevation Control Mechanism (T1548); ranked at the 40th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.

The strongest mitigations our analysis identified map to AC-3 (Access Enforcement) and AC-4 (Information Flow Enforcement) — see the control section below for these in your framework.

Deeper analysis AI-assisted summary

Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.

CVE-2025-65318 is a high-severity vulnerability (CVSS 9.1, CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N) affecting Canary Mail versions 5.1.40 and below. The issue arises in the attachment interaction functionality, where the application saves documents to the file system without applying the Windows Mark-of-the-Web (MOTW) tag. This flaw, classified under CWE-693 (Protection Mechanism Failure), enables attackers to bypass built-in file protection mechanisms in the Windows operating system as well as third-party security software.

A remote attacker with no privileges or user interaction required can exploit this vulnerability by delivering a malicious document via email to a victim using the affected Canary Mail version. When the victim interacts with the attachment, the application saves it to disk lacking the MOTW tag, allowing the file to execute without triggering security warnings or blocks. Successful exploitation grants high confidentiality and integrity impacts, potentially enabling arbitrary code execution, malware persistence, or data exfiltration without detection by host protections.

Vendor advisories and additional details are available at http://canary.com and http://canarymail.com, with technical analysis and proof-of-concept resources on GitHub at https://github.com/bbaboha/CVE-2025-65318-and-CVE-2025-65319, alongside a Google Drive link at https://drive.google.com/file/d/14wrTzvcLPfFsWmy-SAtDwwZKKPssBsx5/view and https://github.com/nickvourd/RTI-Toolkit. Security practitioners should consult these for patch information and mitigation guidance, such as upgrading Canary Mail beyond version 5.1.40.

OWASP Top 10 for Web (2025)

A06:2025 Insecure Design

EU & UK References

Vulnerability Data

When using the attachment interaction functionality, Canary Mail 5.1.40 and below saves documents to a file system without a Mark-of-the-Web tag, which allows attackers to bypass the built-in file protection mechanisms of both Windows OS and third-party software.

CWE(s)
CWE-693

Related Threats

MITRE ATT&CK Enterprise Techniques

T1548 Abuse Elevation Control Mechanism Privilege Escalation
Adversaries may circumvent mechanisms designed to control privilege elevation to gain higher-level permissions.
attack.mitre.org →
T1553 Subvert Trust Controls Defense Impairment
Adversaries may undermine security controls that will either warn users of untrusted activity or prevent execution of untrusted programs.
attack.mitre.org →
T1553.005 Mark-of-the-Web Bypass Defense Impairment
Adversaries may abuse specific file formats to subvert Mark-of-the-Web (MOTW) controls.
attack.mitre.org →
T1600 Weaken Encryption Defense Impairment
Adversaries may compromise a network device’s encryption capability in order to bypass encryption that would otherwise protect data communications.
attack.mitre.org →
T1689 Downgrade Attack Defense Impairment
Adversaries may downgrade or use a version of system features that may be outdated, vulnerable, and/or does not support updated security controls.
attack.mitre.org →
T1040 Network Sniffing Credential Access
Adversaries may passively sniff network traffic to capture information about an environment, including authentication material passed over the network.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2026-7978Shared CWE-693
CVE-2023-25080Shared CWE-693
CVE-2024-20284Shared CWE-693
CVE-2025-29864Shared CWE-693
CVE-2026-44071Shared CWE-693
CVE-2026-44003Shared CWE-693
CVE-2026-0045Shared CWE-693
CVE-2023-35352Shared CWE-693
CVE-2026-47139Shared CWE-693
CVE-2024-0014Shared CWE-693

Affected Assets

canarymail
canary mail
≤ 5.1.40

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

—

Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)
  • 8 hardening rules · 6 OS baselines
Validate
Prove the fix (OWASP ASVS)
  • V6.3.3
  • V6.6.3
  • V10.2.2

Mitigating Controls (NIST 800-53 r5) AI

AC-3 Access Enforcement good match

AC-3 directly requires enforcement of access authorizations via the protection mechanism itself.

AC-4 Information Flow Enforcement good match

AC-4 mandates use of information flow enforcement mechanisms to control data movement.

SC-2 Separation of System and User Functionality good match

SC-2 requires separation of user and system functionality as a protection mechanism.

SC-28 Protection of Information at Rest good match

SC-28 requires protection mechanisms for information at rest.

SC-3 Security Function Isolation good match

SC-3 requires isolation of security functions from non-security functions.

SC-7 Boundary Protection good match

SC-7 requires boundary protection mechanisms to monitor and control external communications.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.AA-03 mostly match
prevents

Enforcing authentication directly implements a core protection mechanism whose absence or misuse is the CWE.

PR.AA-05 mostly match
prevents

Defining and enforcing access authorizations is a protection mechanism; proper use prevents the CWE.

PR.DS-01 mostly match
prevents

Cryptographic and integrity controls are protection mechanisms whose correct deployment mitigates the CWE.

PR.DS-02 mostly match
prevents

Encryption and integrity protections for transit are explicit protection mechanisms.

PR.IR-01 mostly match
prevents

Logical network protections are protection mechanisms whose failure matches the CWE.

PR.PS-01 partial match
prevents

Hardened configuration baselines ensure protection mechanisms are correctly applied and maintained.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.5.36 Compliance with policies, rules and standards for information security partial match
finds

Systematic verification that security mechanisms operate according to defined standards reduces the likelihood that protection mechanisms are bypassed or disabled.

A.8.20 Networks security partial match
mitigates

Hardening devices, disabling vulnerable protocols, and maintaining accurate network diagrams reduce the likelihood that a protection mechanism is misconfigured or left in a weak state.

A.5.24 Information security incident management planning and preparation none match
none

Requiring defined escalation paths, crisis activation criteria, and coordination procedures strengthens the overall protection mechanism so that a single control failure is less likely to leave the organization exposed.

A.5.25 Assessment and decision on information security events none match
none

By requiring a documented categorization and decision process for security events, the control ensures that protection mechanisms are not bypassed or ignored when anomalies occur.

A.5.26 Response to information security incidents none match
none

Identifying and remediating control weaknesses that contributed to an incident reduces the likelihood that protection mechanisms will fail again.

A.5.27 Learning from information security incidents none match
none

Post-incident analysis that feeds updated risk assessments and additional controls directly reduces the chance that previously exploited weaknesses will recur.

Hardening callouts derived

Configuration rules from DISA STIG baselines that bear on weaknesses of the type cited by this CVE. Each rule is shown with the relationship its mapping actually records, against the CWE it was authored against. Derived via CVE→CWE over `controls_xwalks` (authoritative rows only; rows rated `none` are excluded).

Oracle Linux 8 (2 rules)
  • V-248524 OL 8 must implement NIST FIPS-validated cryptography for the following: To provision digital signatures, to generate cryptographic hashes, and to protect data requiring data-at-rest protections in accordance with applicable federal laws, Executive Orders, directives, policies, regulations, and standards. prevents CWE-693
  • V-248525 All OL 8 local disk partitions must implement cryptographic mechanisms to prevent unauthorized disclosure or modification of all information that requires at-rest protection. prevents CWE-693
Windows 10 (2 rules)
  • V-220865 The Windows Remote Management (WinRM) service must not use Basic authentication. prevents CWE-693
  • V-220812 Credential Guard must be running on Windows 10 domain-joined systems. prevents CWE-693
Windows 11 (1 rule)
  • V-253418 The Windows Remote Management (WinRM) service must not use Basic authentication. prevents CWE-693
Windows Server 2016 (1 rule)
  • V-225012 Windows Server 2016 must be running Credential Guard on domain-joined member servers. prevents CWE-693
Windows Server 2019 (1 rule)
  • V-205907 Windows Server 2019 must be running Credential Guard on domain-joined member servers. prevents CWE-693
Windows Server 2022 (1 rule)
  • V-254441 Windows Server 2022 must be running Credential Guard on domain-joined member servers. prevents CWE-693

References