CVE-2024-7209Known exploitationNetwork attack vector

Authenticated sender spoofing via shared SPF trust

Published Jul 30, 2024 · Updated Feb 13, 2025

Authentication bypass in Fastmail allows remote authenticated users to spoof senders on other hosted domains through its outbound mail service. The multi-tenant mail path treats network or SMTP authentication and shared SPF authorization as sufficient without verifying that the account controls the From domain. An account on one hosted domain is enough to send cross-tenant messages that receiving services can accept as DMARC-aligned and valid.

CVSS severity6.5
Medium
EPSS probability0.32%
Next 30 days · Sep 16, 2026
Known exploitationReported
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authentication bypass in Fastmail allows remote authenticated users to spoof senders on other hosted domains through its outbound mail service. The multi-tenant mail path treats network or SMTP authentication and shared SPF authorization as sufficient without verifying that the account controls the From domain. An account on one hosted domain is enough to send cross-tenant messages that receiving services can accept as DMARC-aligned and valid.

The record

CVE
CVE-2024-7209
Published
Jul 30, 2024
Updated
Feb 13, 2025
Vendor
Fastmail
Product
Fastmail
Classifications
CWE-290, T1036
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jul 30, 2024CVE publishedPublication date reported by the CVE source.
  2. Feb 13, 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?

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

  1. Affected versionversion=Current

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Fastmail · Fastmailversion=Current

Published CVSS scores

6.5CISA-ADPCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationReported
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-290Authentication Bypass by Spoofing
T1036Masquerading

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.

Reported exploitation

Technologies

Your stack

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Your stack

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