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Vulnerability record · CVE-2024-27938 · published 11 March 2024

CVE-2024-27938: Postalserver postal vulnerability

Postalserver · Postal

Postal is an open source SMTP server. Postal versions less than 3.0.0 are vulnerable to SMTP Smuggling attacks which may allow incoming e-mails to be spoofed. This, in conjunction with a cooperative outgoing SMTP service, would allow for an incoming e-mail to be received by Postal addressed from a server that a user has 'authorised' to send mail on their behalf but were not the genuine author of the e-mail. Postal is not affected for sending outgoing e-mails as email is re-encoded with `<CR><LF>` line endings when transmitted over SMTP. This issue has been addressed and users should upgrade to Postal v3.0.0 or higher. Once upgraded, Postal will only accept End of DATA sequences which are explicitly `<CR><LF>.<CR><LF>`. If a non-compliant sequence is detected it will be logged to the SMTP server log. There are no workarounds for this issue.

5.3 CVSS 3.1 Medium EPSS 0.66% · top 50.2% CWE-116 · CWE-116
5.3CVSS 3.1 base score
0.66%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
8References, 2 tagged exploit
17 Jun 2026Last modified by NVD

Description

Postal is an open source SMTP server. Postal versions less than 3.0.0 are vulnerable to SMTP Smuggling attacks which may allow incoming e-mails to be spoofed. This, in conjunction with a cooperative outgoing SMTP service, would allow for an incoming e-mail to be received by Postal addressed from a server that a user has 'authorised' to send mail on their behalf but were not the genuine author of the e-mail. Postal is not affected for sending outgoing e-mails as email is re-encoded with `<CR><LF>` line endings when transmitted over SMTP. This issue has been addressed and users should upgrade to Postal v3.0.0 or higher. Once upgraded, Postal will only accept End of DATA sequences which are explicitly `<CR><LF>.<CR><LF>`. If a non-compliant sequence is detected it will be logged to the SMTP server log. There are no workarounds for this issue.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/postalserver/postal/commit/0140dc4 Patch
https://github.com/postalserver/postal/security/advisories/GHSA-j42r-6c99-hqf2 Vendor Advisory
https://sec-consult.com/blog/detail/smtp-smuggling-spoofing-e-mails-worldwide Technical Description
https://www.postfix.org/smtp-smuggling.html Exploit
https://github.com/postalserver/postal/commit/0140dc4 Patch
https://github.com/postalserver/postal/security/advisories/GHSA-j42r-6c99-hqf2 Vendor Advisory
https://sec-consult.com/blog/detail/smtp-smuggling-spoofing-e-mails-worldwide Technical Description
https://www.postfix.org/smtp-smuggling.html Exploit

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2024-27938), CISA KEV, FIRST EPSS (scores of 2026-09-29). This page is refreshed as NVD updates the record.