CVE-2021-44549Network attack vector

Email interception via disabled SMTPS hostname verification

Published Dec 14, 2021 · Updated Aug 4, 2024

Improper certificate validation in Apache Sling Commons Messaging Mail 1.0.0 allows man-in-the-middle attackers to read or alter email. SimpleMailService creates a shared JavaMail session without setting mail.smtps.ssl.checkserveridentity, so TLS accepts a trusted certificate for the wrong server name. Exploitation requires interception of the SMTPS connection and presentation of a certificate trusted by the client.

CVSS severity7.4
High
EPSS probability1.94%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper certificate validation in Apache Sling Commons Messaging Mail 1.0.0 allows man-in-the-middle attackers to read or alter email. SimpleMailService creates a shared JavaMail session without setting mail.smtps.ssl.checkserveridentity, so TLS accepts a trusted certificate for the wrong server name. Exploitation requires interception of the SMTPS connection and presentation of a certificate trusted by the client.

The record

CVE
CVE-2021-44549
Published
Dec 14, 2021
Updated
Aug 4, 2024
Vendor
Apache Software Foundation
Product
Apache Sling Commons Messaging Mail
Classifications
CWE-295, T1557
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 14, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

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  1. Affected versionversion=Apache Sling Commons Messaging Mail 1.0.0 1.0.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Apache Software Foundation · Apache Sling Commons Messaging Mailversion=Apache Sling Commons Messaging Mail 1.0.0 1.0.0

Published CVSS scores

7.4NIST NVDCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
5.8NIST NVDAV:N/AC:M/Au:N/C:P/I:P/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.

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-295Improper Certificate Validation
T1557Adversary-in-the-Middle

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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